> Hey, the government can decide whether something qualifies as grounds to revoke a green card or not, that's totally legitimate and I support it.

No, it can't. It must go through a process which affords the green card holder due process. There are specific grounds which are required to be met to remove someone's green card.

And it absolutely cannot be revoked because the government disfavors ones political speech. That's an absolutely fundamental violation of the first amendment and our right to free speech.