I think actually saying "unduly offend" is so quirky and strange that it won't come off as weak. It'll sound like he's having fun with it, and doesn't really care if it offends at all. In fact, he's saying he doesn't care if it offends - as long as it doesn't "unduly offend". I'm tempted to try adding "would it unduly offend you..." to a lot of things now..
