One: there is no evidence they were creating a "tent city" or taking any actions that violated school policy
Two: and this is a big one, you don't seem to understand what freedom of speech means. Open areas on campus (e.g., the south lawn) are part of the public forum and available to the public for assembly by law. The government (i.e., the police and UT) does not get to prevent speech because they do not like the content. It does not get to restrict the freedom of assembly because it does not like the content of speech. UT isn't a private actor. These aren't private lands. The Constitution gives those students the right to assemble and speak there. The University destroyed those rights. Why you're ok hand waiving the violation of core civil rights is absolutely beyond me.
Three: the University should have allowed them to gather and to speak. Only if the gathering starting getting threatening, violent, destructive, or overly disruptive of school (e.g., barring people from class), should the police have been called in.
But sure, you just ignore core rights because you don't really care what the speakers have to say.