Obama's jokes about McCain are truthful. They do not rely on appeals to bigotry or meanness. I would say therefore they are more "ironic" than "sarcastic".

In any case, a sword wielded in self-defense is completely different from a sword wielded in a bullying attack. The Republican convention and campaign are full of pure sarcasm. After taking many punches, Obama is merely punching back with the truth. Equating his tactics with McCain's is absurd.