Done a similar thing in a Zoom interview. I had a horrible hard Leetcode question, was completely stuck and was getting nowhere (neither did the interviewers seemed keen on helping me out). I told them hey thanks this isn't my day I want to quit the interview - at this point they really tried hard to make me stay for the rest of the time. I think if a candidate wants out - you should let him.
I was referred to this company through a past colleague that was currently working there so it's possible they didn't want to bum out this person, but I actually don't think that was that - they looked genuinely surprised and a bit shocked when I wanted to stop which I can understand, it's not something that happens often at all. I think they just felt it was 'wrong' for an interview to be stopped short by the candidate and tried to rectify the situation.
