While the idea of forced patriotism is a contradiction, and Steinbrenner is an idiot for imposing the rule (I would expect crowds to be self-policing in this matter in any case), this clown sounds like a complete douche. He was challenged by the stewards and, instead of simply saying "I reeeeally have to piss.", he chose to be snide and inflammatory.
He shouldn't have been thrown out of the stadium for going to pee during the singing of GBA, but if you want to be treated respectfully, you should treat others respectfully. Act like a tit, and you'll get frog-marched down the tunnel. See sow, reap.