And that's the problem with extreme responses to abhorrent speech: they give it a bigger platform and a wider audience. Snyder has given Phelps the chance to have the Supreme Court validate him. If anyone thought the man was insufferable before...
I would put it more simply. It's a rational response to a madman who (rightfully) feels his rights are being violated.
Phelps DID go to law school and was once a practicing lawyer. Getting disbarred didn't stop him from building the perfect case when a state passed an unconstitutional law.