

IMO you’re overthinking it.
The Constitution applies to all people within jurisdiction of the United States. Immigration or citizenship status isn’t a factor; he absolutely has a first amendment right to say what he said.
The question you’re struggling with is regarding people who aren’t already within the jurisdiction, or are applying for citizenship.
All of that said, if ICE already deported him then that complicates things. Normally somebody who’s been deported will be denied reentry for that reason alone; there’s a waiting period (5 years iirc) if they’re ever going to be allowed back in at all. But you’re correct that they could also deny him reentry for his political views. It’s likely that, if he’s already out of the country, legally removed or not, a judge will have to order him to be allowed reentry despite both of this things.
Huh. TIL.
I guess this is exactly what the judicial branch was created for. We’ve got an undefined area of legality, somebody’s got to sort it out, and until they do we just can’t say for sure one way or the other