Seems like Maher had no arguments, came up with a stupid joke, and then tried to defend himself in an aggresive way which was lacking logic.
I hope the "joke" is not resembling the general attitude of the U.S., because otherwise it means NATO is really weak. The same attitude was present in the UK and other countries (also the U.S.) when Hitler "was taking" Poland in 1939. If the U.S. is sleeping at the moment (since Maher wants someone to "wake him"), history may be repeated very soon.
A joke is supposed to be funny. This was simply disrespectful.