To be offensive, the show would have to display the Axis powers in a positive light.
And even if it did, it’s none of de Butthead’s business.
I am offended when I turn on the TV and see two men (or two women) playing tongue hockey. What’s he got to say about that?
Or when I see men in drag and S&M garb marching in a St. Paddie’s Parade. What’s he going to do about that?
To answer your questions, you have to remember he is liberal. Liberals are not offended by homosexual activity or outlandish sexual innuendo at a parade. Since liberals aren’t offended by that, in fact, they like to push things in people’s faces, it’s all good.
On the other hand, if you do anything to offend a liberal, they call for censorship or banishment for the offending party.