“Non-citizens are here under sufferance.”

To claim that fundamental human rights guaranteed by the constitution do not apply equally to citizens and non-citizens is the height of absurdity. No legal authority supports that conclusion. That is not hand-waving; that is a legal fact.

Rather it is that IF they are here they may not be denied fundamental legal rights, but there is no right at all for non-citizens to enter the country to begin with and the Congress may make whatever laws they wish for allowing legal entry into the country, no matter how absurd or “unfair” such laws may be.

And insofar as free speech is concerned, the general key is this:

(1) You can advocate anything, no matter how vile, if it is phrased as “I think the law/Constitution should be changed to [examples: re-institute slavery, kill all the gays, institute Sharia law in the US, whatever], its protected.

(2) Urging others to break existing laws can get you into a lot of trouble, unless:

(3) If the law you’re urging others to break really is unconstitutional, you may get vindicated down the line. But beware, you may beat the rap but you won’t beat the ride along that far and perilous journey. And before you undertake it, be very, very, sure that the highest Court that can consider the issue will agree with you. And you have no assurance (none whatsoever) that the controversy will ever get to that level.