> He could feel sudden hostility from everybody in the room at the time.
Sounds like he made a good call here. With a professional interviewer, the worst you might get is "perhaps you could help us by explaining why you feel that way?" Who would seriously want to bully someone into staying to be interviewed for a job they didn't feel they could do? Personally I would thank him for his honesty.
Is it usual to have a team of people interview someone, rather than a lot of one-on-one or two-on-one sessions? This reduces the number of developer-hours used in interviewing. I don't think that adding a 3rd or more interviewer will add anything, and it can be intimidating for candidates, adding noise to your search for a suitable one.
In a couple of decades of occasional job interviews, I've done mostly 1:1 and a handful of 2:1.
I've only done one 4:1, which was actually lunch in between all-day 1:1 interviews, and which didn't feature any technical questions just random social conversation. It was definitely still part of the interview, though.
Sounds like he made a good call here. With a professional interviewer, the worst you might get is "perhaps you could help us by explaining why you feel that way?" Who would seriously want to bully someone into staying to be interviewed for a job they didn't feel they could do? Personally I would thank him for his honesty.