The article states that the school allows swastikas, so I'm guessing that Che or Mao shirts would have been embraced with the sort of warm fuzziness that Leftists reserve for 'young fellow-travellers".
I haven't been to this particular community and I don't know what their ideological demographics are like. I've heard some Texans here at FR refer to Austin as "the Berkeley of Texas" and so I guess even the Great Lone Star State has it's pockets of Leftist insanity.
Here in Western Washington, Che or Mao T-shirts wouldn't be given a second glance. "sigh"
Austin is also known as "Moscow on the Colorado" or the "Peoples Republic of Austin"