There's a lot of little things that just added up, but I think the clearest example was the exchange regarding Andrew's pay from the foundation. I don't have an issue with him being paid for the work, or the amount he's taking, I would be surprised if anyone really did, but the way the interview asked the question came off as "Oh you're only making x? You should be paid so much more", and Andrew even commented in it saying "...it sounds like you're implying I deserve more...". I'm of course paraphrasing, but that's the impression I walked away with.
The questions also had a tendency to be somewhat shallow. There were a lot of places where it felt like the interviewer was queuing Andrew to respond to criticism or explain controversial choices made for the language or tool chain, but the interviewer doesn't really follow up on them are point out what the issues might be.
It might have been expectations I guess. I was hoping for an interesting technical interview and instead it seemed like a fluff piece.