there is a longstanding known, and in many places, WRITTEN, rule, about security-related jokes in airports. everybody knows the TSA is incompetent. everybody who travels frequently knows how absurd the rules are. and there are places, in life, to protest, to exercise your 1st amendment rights, to let everyone in power know just how you feel.
but if you actually care about getting from place A to place B, on time, you are a fool to also simultaneously make a stink in the airport about a t-shirt.
i'm sure people may disagree, on principle, but there's a choice you have to make here - principle or pragmatism. yes, our freedoms and rights are important, and so is getting home on the flight of my choice. with the tight timings and uptight travel workforce, you just can't do both in the same day.
i might have a different view if there was ANY chance this guy's t-shirt would actually change someone's mind, change a policy, make any difference whatsoever. instead, it sounds like he simply exacerbated the problem that he complains about - making ignorant strangers on the plane ever more uncomfortable. those other people on the plane will likely not understand his message and find even MORE things to be fearful of, thus counterproductively reinforcing the foundations of our silly security m.o. that he despises.