SJW is right, favoring social institutions is a legitimate exercise of policy. Lets remember our government is a republic, when the governments acts legitimately they speak with the will of the people. I don't want to live in a society that is powerless to regulate behavior. If I can't take my children to the park (future tense I don't have children yet) cause I can't and the lawmakers can't stop a couple from performing lewd acts in the park, than whats the purpose of living in a society anyway. Favoring a language for example is legitimate in the same, though the policy behind regulating it would be much more suscept than my extreme example. Like I said earlier, I think the immigrantion is a policy question not a constitutional question.
Yes restrictions require justifications-in the political process if there was no justification, nobody would take the proposal serious, the justification is national security (a total joke) and the much stronger justification of cultural cohesiveness, and also a quasi-economic justification, which in the words of south park would be "they took err jobbss" or something like that I can't remember the quote to well.