No. They have a right to sign anyone thery want.
Serving his prison sentence gives him the right to freedom from prison. It doesn't give him the right to walk back into a job at the top of professional sports, make millions of dollars a year and return to his celebrity status.
Anyone that wants to watch an Eagles game is buying a service from the Eagles. What they do with that revenue is their business. If you don't like any of their business practices that much, don't buy their service. Otherwise its none of your damn business.