Actually...yes, purely considering freedom of speech, I would allow WBC to embarrass themselves with their BS as long as everyone understood when their own funeral was desecrated (that said, doesn't really work because they'll be dead...but people can still call them whatever they want while they're alive).
But what the WBC does should be at least public nuisance, even harrassment, slander perhaps. It's despicable, and there are already plenty of laws that could be applied to their antics.
Another thing about freedom of speech, it isn't absolute. You can't slander (anyone with money at least), you can't impersonate police officers (and I suspect a lot of other kinds of people), you can't lie in court, you can't give a false name for most official things, etc.
Captcha: taco tuesday. I thought I'd put it here because clearly it's meant for someone who reads this, because it has no significance to me.