Because it's fundamentally unreasonable to hold one company responsible for the actions of another on the basis of a common shareholder and executive? The rule of law (or at least the generally consistent appearance of it) is far preferable to the open rule of man in wantonly levelling attacks against everyone and everything associated with someone that a government official dislikes.
These judges are known for punishing family members of the people they go after. I've recently seen news of their censorship of social media accounts of a politician for "fake news" or some other nonsense, and they censored the accounts of his wife as well. Faceless corporations probably mean nothing to people like these. They want Musk, they see Musk's name on Starlink, they go after Starlink.
Is it unreasonable when the executive and shareholder in question is in their personal capacity flagrantly opposed to compliance and also professionally trying to avoid compliance with a previous court ruling by removing more pertinent assets? And the satellite network itself is a delivery mechanism if/when X gets blocked in Brazil, so there's reason to preemptively seize that given Musk's public statements on this topic.
(In case it isn't obvious: I'm not a lawyer, I've not really considered this in any depth beyond some other news sources besides this tweet, and this is a totally noob question that may have an answer in literally lawschool 101).
I can't answer to legality since IANAL and systems vary anyways, but on a moral basis, yes, it is absolutely nonetheless unreasonable until SpaceX / Starlink actually commit an actionable offense of their own or otherwise demonstrate the intent to do so. It's outstandingly unreasonable and offensive to seize assets of such an entity without charging that specific entity with an offense; especially so when your basis is literally "I want to compel an unrelated venture with common beneficial ownership to unilaterally censor my political opponents worldwide".
AFAICT, Starlink complies with local regulations in the countries it operates in, including blocking access to specific IP prefixes and/or declining to default resolve DNS entries for specific domains.
Musk said you can use Starlink to circumvent the block if X gets blocked in Brazil.
IANAL but I'm pretty sure this is legal ground enough (plus all the shit Musk spits on Twitter, attacking Brazil and its institutions, a criminal offense in Brazil, from his ivory tower in Texas) to solicit a block of Starlink Holdings assets.
There are plenty of reasons out there to justify these actions and you can be sure Moraes will find them.
EDIT: Musk said this in April during Twitter Files Brazil.
Unfortunately he deleted the tweet and I can't find it anywhere, but it was mentioned during the whole "Twitter Files Brazil" saga where Musk explicitly said "Starlink userd won't be affected if X gets blocked".
Musk is well known to tweet inflammatory, controversial, or fake stuff and delete the tweet after few days.
I personally observe some of his viral tweet to be deleted later multiple times.
At some point I had a burst of motivation to start writing a bot to keep track of all the stuff he deleted for people like you to observe, but was quickly disgusted to waste any time to be on top of the argument with some stranger.
So yeah, without google or other search engine's ability to index the whole twitter, everything is written there is hearsay I guess.
As a Brazilian citizen, X / Musk have broken the law and have been fined. The fines are meant to compensate for damages done against my country. I absolutely want that debt to be paid. Moraes, within the boundaries of the law, has seized assets from another company that belongs to the same individual who's committing those crimes and is trying to evade punishment by closing the fined company. This should never be allowed to be used as a means to evade punishment.
From where I'm standing, this is legal security - not the opposite. In fact, I don't know if the law would allow it, but morally I would be fine with Musk being given a prison order or other sanctions for using such artifices in an attempt to evade justice.
Musk owns 42% of SpaceX, Starlink is a subsidiary.
I can't speak to SpaceX shareholders because they are private, but of the public Tesla that's also associated with Musk, there are shareholders who want him out because his public behaviour is interfering with the business interests, and that argument will gain weight as a result of stuff like this.
Is that "deserved" depends a great deal about how you model the entire world, but activists investors are a thing and they do fight company management.
You have no idea how much disinformation there is in Brazil. Its basically 24/7 information warfare there, from both sides. I have family there, I was blown away by how aggressive it all was when visiting last year.
The only time they tried to do tracking on where these posts and sockpuppets were coming from, they ended up in Israel (this is a common practice, I'm assuming to make tracing and legal action more difficult. In Portugal the bots come from Angola).
Its clear that the same disinformation farms that are running in the US were duplicated to Brazil, by the same people (Bob Mercer / Steve Bannon). Proof of that was of course, the deeply personal relationship between Bannon and the Bolsonaro family (when he was out of jail he would visit all the time), and the faux January 6th that was replicated in Brazil after Bolsonaro's defeat.
You have to understand that the population of Brazil has A LOT less education than the population in the US or Europe. They are far more malleable to disinformation.
One of the worse examples I can think of is the disinformation campaign that was activated after the murder of Marielle Franco, who was tagged in fake photos with local Rio drug dealers - while she was still dead inside her car. So a few minutes after the murder, you had a giant disinformation campaign launched. Since it was so fast, the only reasonable conclusion is the murderers control a disinformation bot/sockpuppet farm.
He ignored court orders, he broke the law. By (repeatedly) doing that, he enabled terrorist groups and disinformation networks to attack Brazilian society and democracy.
Just so we are clear, you're saying that Twitter/X should continue to operate in the country so it'll be subject to their law instead of choosing up shop and avoiding dealing with what they think are unreasonable demands?
If Twitter doesn't want to follow the laws of Brazil, then they need to stop providing access to Brazil.
Merely having no office in some country not sufficient, for the same reason it wasn't sufficient for preventing New Zealand based Kim Dotcom to be prosecuted (and his Hong Kong-based Mega Upload domain to be seized) by the USA.
Or all the defamation suits against US citizens filed in the UK on the grounds that being published on the internet counted as if it was published in the UK, forcing the US (Federal and State) to pass laws preventing payment of penalties in such cases: https://en.wikipedia.org/wiki/Libel_tourism
Edit:
Just found an interesting claim, thought I cannot verify it myself:
"Under Brazilian law, social networks must have a representative to receive and consider government takedown notices about political misinformation. X has no such person after closing down its Brazil office. Moraes gave the X platform 24 hours to name a new legal representative or face a nationwide suspension." - https://www.siliconrepublic.com/business/x-brazil-suspension...
