Oh, I agree, by itself it isn't a danger, I suppose it's just ridiculous to my mind that we would need a law telling people to respect the feelings of a murdered 9 year-old girl's family, I'm pretty sure that the Founding Fathers of the US expected people to exercise a certain level of self-control using their own intelligence and not just pointing blindly at the document and saying "But it says I have the right to!". That thinking risks turning the Constitution from a 'living, breathing document' into, almost, religious doctrine.
It's a Catch 22 situation, I've always respected the US Constitution, for all the arguments over interpretation, it's probably one of the best intentioned documents in the world, but I seem to recall that it mentions the 'Right to Dignity', and that, I think, is what people should be aiming at when dealing with the Westboro protests, protesting at a funeral is abusing the victims right to dignity.