I never claimed it was a perfect analogy - I still think it's a better one than the Salmon Pictures.

Well you're right about that at least.

How would you personally feel about a national "draw Martin Luther King with big lips eating watermelon" day, done by foreigners? I don't expect you'd go out and burn stuff, but I also expect you'd prefer it didn't happen

That's precisely the point.

(if this doesn't apply to you you, it probably does to quite a few Americans on this site, I don't even know if you're American). I mean, I tend to be a pro-free-speech bullet biter, but I wouldn't like it.

Well, after the US Supreme Court ruled in favor of the Westboro Baptist Church's right to free speech, all the major newspapers ran editorials supporting the decision. In fact, this blog post argues that its easier to support free speech for extreme groups like the WBC since you get free warm fuzzies for supporting free speech without having to worry that they'll actually persuade anybody.