On the one hand, I am largely "pro people" and there's no question that humans have an amazing capacity to perform intellectual and creative feats that are mind blowing. But situations like this remind me that humans also have a nearly unlimited capacity for stupidity.

Seriously, how fucking stupid do you have to be to do something like this? Even if they were right that the question reflected poorly on the candidate somehow (which seems unlikely), you don't send an email like that and not expect it to blow up in your face.