You guys know I'm not a big fan of lawsuits. But the case here is pretty clear-cut. He was off duty, being Joe Citizen and protested. He works for a Gov't Agency, so that means punitive actions taken against him BY the NJ Transit are bound by the Constitution. In this case, he was fired for using his Right to Free Speech in a civilian capacity. That's what is the issue here.
If he worked for Bob's Toll Booths Inc. this would be an entirely different story. Private companies are not Gov't Agents and thus punitive measures by them are NOT bound by the Constitution. (General rule, obviously there are civil rights, and other areas this applies) however, in the case of Free Speech this is not so.