[JeremyD]

Just as some people don't know how to present themselves in an interview - some interviewers don't know how to interview either.
he might - or might not present himself differently when working there.

Taking a job is a leap of faith by both parties. I've seen people that came across as superheros turn out to be lumps on a log - and I've seen people muff an interview and be great employees. It's a snap shot in time.

Don't limit your options. if he was that bad - by getting your foot in the door - maybe you could end up running the place. stranger things have happened.