You have to mention this precisely because it's disingenuous to hide behind the purely non-political justifications of the boycott - you end up trying to draw up a non-political dividing line which just so happens to exclude the viewpoints you have political objections to.

Except that it doesn't exclude viewpoints I have political objections to. It excludes people who are willfully ignorant and who refuse to engage with arguments and follow standard rules of intellectual discourse, regardless of what they happen to believe. It applies to atheists just as impartially to creationists, if they happen to engage in the same kinds of intellectual sleaziness. I never suggested that it would only damn creationists, just that it would be especially damning to creationists. And for what it's worth, I've had this personal test for distinguishing between people worthy of debate/discussion and people who are a waste of my time for much, much longer than I've had a distaste for creationism.