There's no straw man in the argument you're replying to. All that was said was "maybe the idea that things should be censored is a bad idea and should be censored." It is a very clever way to demonstrate the danger of what you're potentially prepared to embrace, and how it can be used against you.
Nobody can hold a monopoly on the marketplace of ideas. Nobody. That genie is out of the bottle.
No, it is a straw man. The idea that crazygringo highlighted was simply the notion that maybe the best ideas don't win in a free marketplace of ideas. The straw man presented was that you wouldn't be able to discuss this at all if there was no free speech.
But there are regulations on free speech and they are sensible. My understanding of speech regulations in the USA is that they primarily need to be focused on time, place and manner restrictions unless they fall into some exceptions that typically don't matter (edit: typically don't matter in political discussions).
A sensible manner restriction: you will generally be told to move along if you are shouting your message at the top of your lungs in a public place. Especially so if it is the middle of the night.
How you speak your message can be regulated in a more easily balanced way, although it is somewhat dangerous as well. This leads to potential place, manner restrictions online. A manner restriction can easily be content neutral.
A manner restriction: you could maybe regulate the use of sock puppets or fake accounts.
Here you see it is a strawman argument to say we could not have a discussion regarding whether good ideas will win in a marketplace where sock puppets are banned.
Nobody can hold a monopoly on the marketplace of ideas. Nobody. That genie is out of the bottle.