There are places for expression and "Free Speech"... maybe sitting next to the 13 year old or grandmother (or any other paying customer) who's flying for the first time in his/her life wearing some silly t-shirt about bombs and anti-government banter isn't the right place for it.

Does this then imply I don't have a right to live, because "rights cannot be denied based on the ability to pay"? That I don't have a right to property, because if I don't pay my debts my belongings can be confiscated and sold at auction?

I have a right to appoint my own counsel, but the government won't pay for the counsel I appoint. In order to use that right I have to be able to afford the lawyer I want.

US citizens have a right to run for elected office, but clearly that's not provided free of charge!

Rights are not irrespective or independent of my ability to pay. And if something is a right does not mean I get it for free.

I think you need to lay out your argument in greater detail than you have done so far.

To say that carriers should be able to selectively revoke this abstraction and deny travel to specific individuals is to give them the power to force arbitrary rules on anyone who relies on this infrastructure. This would make all rights subject to the whims of the airlines.

The idea is that Congress cannot criminalize speech. But the ramifications of your free expression, with respect to those people and institutions that you interact with, is not regulated by congress in so far as a crime is not committed in reaction.

Could McDonald's legally deny me entry to their restaurant if I was wearing a T-Shirt that said "I support Obama"?

Further, can they legally deny me entry for no reason at all?

(I'm not trolling, I genuinely don't know the answers)

Edit: I guess specifically if being in that protected group played into why you were denied. Meaning, they can toss you for being drunk even if you're in a wheelchair.