American Airlines American Airlines unfair and business practices with questionable legality El Paso, Texas

I was supposed to fly round trip to Austin Texas then scheduled a business trip in Hong Kong from NYC with a return to Austin so I wouldn't have to change my plans for Austin.

American Airlines says that since I didn't fly there on the first ticket the second ticket is invalid due to security concerns having to do with 911. 

They didn't notify me at all of this until I was standing in line at the airport to get my boarding pass. They claim that I consented to the agreement when I purchased myticket which in fact was purchased for me in my name but not by me so I was completely unaware of such terms nor was I sent the terms with the e-ticket.

The only option to get from Austin to NYC was to buy my seat again, which was vacant. Say I sell you a Happy Meal, you decide that you wish to not eat the fries, can I take your money, give you change then when you tell me that you don't want to eat the fries, tell you you have to purchase a hamburger instead for the price of a Big Mac and not refund your Happy Meal?