The way I read that, it's even more dangerous than it looked at first.
I'm from France and so we have the whole hate speech limitation to freedom of speech, that I agree with, it works but has to be well defined and limited to specifical type of things.
What the US gov is arguing here if I'm not mistaken, is that if the US gov wants to go in direction X, anyone arguing for another direction can now be deported even if everything they do and say is technically legal to. You simply have to apply that thinking to anything that isn't as polarized as israel/palestine to see how dangerous of a point of view it is. If the judge don't stop that, I don't see how that can lead to anything other than political persecution of the opposition.