The dot got more "likes" than Khamenei's Tweet. He was able to "ratio" the supreme leader's message without saying anything at all, and apparently the government decided that's worth 12 years in prison.

But was that really the case? Reading the other comments seem to imply that the article had a baity headline

We should probably read the article rather than the other comments. The article does mention that, while the accused's family is unsure of the exact motive, the arrest happened shortly after the "dot" post. Perhaps it was just the most visible form of dissent that they committed just prior to arrest.

I believe he was trying to ratio him (and he succeeded).

Probably similar to https://en.wikipedia.org/wiki/Blank_piece_of_paper.

trying to overwrite the hardlink to current directory, typical cybercrime

your bully replies to your tweet with a single period. you don't know precisely what he means, but you do know he's bullying you. You and your bully are adversaries, he's adversarying you. I'm not saying that Shanbehzadeh is the bully, I'm sure it's vice versa, but if you respond to your bully's post with a single period, prepare to get your ass kicked in school the next day.

it might be fun to play the legal game "but what law did I break" in a country with rights and rule of law, but in a country without it...? I'm pretty sure Shanbehzadeh knew what he was risking.

Would he have gotten just 6 years if he tweeted a comma instead?