The government didn't suspend him, his employer did. The first amendment only protects him from the government.
While I 100% support his actions, I also recognize that it is very much suspension worthy. Now I also question the wisdom of bringing a political figure (ESPECIALLY this political figure), and not expect this type of thing. Actually I wouldn't be surprised if they did expect it, and warned people that disruptive behavior would result in a suspension (still worth it).