This is what petty tyrants do. Tale as old as time, song as old as rhyme.
Only to offer this observation. Commentary so far indicates it was the Secret Service....not the local university ‘owners’ of the building who dictated this. If true....you might as well rename the Secret Service....the ‘T-shirt-squad’ (TSS). The leadership of the Secret Service from the 1960s/1970s....would be embarrassed by this type of leadership and behavior.
Fear of t-shirts....even Jefferson would be laughing in his grave over this. We are no longer a democracy....if you fear t-shirts to this degree.