It was a comparison of the
relationship between the two men (and at that, it was a bit over the top, but, IMO, not an indictable offense). He was not comparing BHO to Hitler anymore than he was comparing Boehner to Netanyahu. He was saying that enemies should not play golf together. Again, people should know NOT to bring Hitler up--AT ALL--but, he was making an analogy, just like they do in the SATs.
For example, it would have been better if he did something like this:
Obama:Boehner = Clinton:Gingrich