I very much like "Abortion is a medical procedure". It's actually a believable WAitW to make, and has the admirable feature that it completely ignores every aspect of abortion relevant to the debate.

I think the "free speech" examples don't quite have the right form: the central question probably is whether or not pornography or flag burning is free speech, and the conclusion "Flag burning is free speech, therefore it should be legal" is valid if you accept the premise.