Guys (in the gender inclusive usage of "guys,") I think most of us get it. She, you, or I should be able to wear a t-shirt with a mildly political message and a comic book hat on a flight.
The question is more, knowing the idiocy of airport "security" practices these days, why would you choose to fight that battle when you have somewhere to be? When I fly, I wear different shoes that are easier to get on and off through TSA. I pay $25 to check my suitcase even though it could be carried on so I don't risk having to be one of the schlubs that has to gate check their bag because the overhead bins are too full. I go through my entire backpack to make sure there's not a nail clipper or something for TSA to lose their shit over. If the airline pulls some bullshit at the gate, I swallow my rage and smile back at them and ask them nicely to resolve it. I try to swing a window seat as often as possible, not because I actually like the seat, but because it offers the least amount of contact with other smelly humans and the least amount of getting out of my seat to let another smelly, piss-filled human by.
It's all bullshit, but I do it anyway because flying sucks and I'm just trying to make it a little less shitty for myself. Yeah, it frustrates me, but I'll pick that fight sometime when I don't have some place to be.