I'll gladly concede that a non-trivial number of the protestors don't have an informed viewpoint on why they are protesting and are simply protesting to protest. That's been the case on the west mall and other college campuses for decades. Young people are always pissed off at the government for a variety of reasons, so when given a chance to protest the government, they will jump right in. Hell, some of them are probably protesting for no other reason than a hot chick they know said she was going to protest.
But I would also argue that claiming the majority of these protestors are antisemitic is fucking laughable. There's one side currently subjugating/annihilating the other right now, and it ain't those poor folks in Gaza. That's what people are protesting. They weren't all out there last June. And while there are almost certainly some antisemites in the group, simply protesting Israel's annihilation of Gaza is by no means antisemitic. That's bullshit. You may agree or disagree with Israel's tactics, but you should be free to voice those beliefs without threat of arrest. I get very uncomfortable when the government starts defining what you can and cannot criticize. You should be free to criticize Israel or free to criticize the Palestinians/Hamas.
I had a reply to your second paragraph (why start at 1967 rather than 1948, etc...), but deleted it as there are threads on this board for discussing the greater Israeli/Palestinian conflict and this thread already suffers from some unfortunate hijacks rather than the protests at UT (see the recent effort at Jewish Taxonomy). I'll just say, I fully expect that region to be a fucking shitshow long after I'm gone from this world. And hopefully students will be free to voice their opinions on the matter without the blessing of whomever happens to be sitting in the governors mansion.