None of us (Americans, I mean) are entitled by inalienable right to enter the EU. You can call an immigration officer an asshole at CDG airport and be given the heave ho. So if they just ban him from the EU for acting in a way they believe is counter to the interests of the EU, then ... fair play? Don't know why you'd want to go somewhere and spend money that doesn't want to have you.

Now, if they try to seize assets that have any connection to Europe, that's a different story.