I carry on the light rail 2x a week. cc if im on my way to ASU, oc if going elsewhere. most tsa's look like they are headed to the 44th st stop to go to work at the airport, and are generally oblivious to the goings-on of the train car anyway. I'd be more worried about the City 'o Phoenix transit cops than TSA's confronting you. Know the law and your rights. Your knowledge is more powerful than any firearm that you have.
honestly, an aviation TSA can "kiss my grits" if i'm not in their "jurisdiction".