> Whether deportation of aliens based on their speech is constitutional is unsettled.

Is it? That would suprise me. The First Amendment does not mention citizenship:

"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

If free speech of aliens were not protected, neither would their practice of religion. "Americans can be Catholics, but we won't let any non-American Catholics in. We have enough of them."