I am a UCI alumnus and former member of the UCI College Republicans, so I will be calling the Alumni Relations Office and express my displeasure, and tell them they are exposing themselves to liability for First Amendment violations, as they are a government entity they can't censor their students or deprive them of freedom of assembly.
No, the Alumni Relations Office does not care what you think.
There is no liability in making you follow University policies.
You can assemble all you want, but if the U requires security, guess what, podjo.