Interesting timing, since I just had thought about that over Shabbat. I think the answer should be clearly no, that what happens within a school community is for the members of that community to weigh in on-- unless the community as a whole decides to take it public. I think that decisions about these kinds of issues are often student-specific, or community specific, and not meant as bold new statements of policy. To the extent that a school decides yes or no for situation-specific reasons, it's nobody else's business.
I also think there's a broader question here, important educationally, that Jews aren't supposed to be living their lives in public (the real definition of tzeniut--see the last page of Makkot, where Michah's call for "hatznea lechet im elokecha" is seen as applying to weddings and funerals, two of the most public events in the Jewish lifecycle). We aren't supposed to announce publicly flaws in our relationship with Hashem ("ashrei nesui pesha, kesui chata'ah"), and we're, in general, not supposed to seek public attention. That's an ideal that Facebook and other social media are countermanding in the eyes of many students. Posting on FB and Snapchat or Instagram or change.org is, to them, not taking it public. That's a broad Jewish error that I think educators should be addressing-- that tzeniut means we don't broadcast in public anything other than that which needs to be, which has a good reason to be broadcast.
