My interpretation of events is that this man's points were perhaps made in a light-hearted manner, and he delivered them badly, and appeared to be serious when he did not intend to be so.
If you are going to speak in public, and have your words reported, then you are prone to the same trap that all of us face on here - your comments in print without the benefit of personal knowledge and face-to-face interaction may be misunderstood, and offence can be taken.
So it behoves the individual to take care over what they say, and how they say it, in order to attempt to steer clear of the sort of trap he has fallen into.
I do not believe it was an offence to resign over, but that is a matter for the gentleman concerned.
I think most people would see it as I have - he spoke carelessly, he was misunderstood, he apologised, he will have learned his lesson, and everyone can move on.
In view of jim's OP - he is clearly not an idiot per se, but academic intelligence is absolutely no protection against a foot / mouth interface.