A friend of mine went on an interview recently for a software developer position at a well known company. It was a senior position, and he had very relevant business experience in the industry. I gave him the highest recommendation having worked with him in the past as a no-nonsense guy that cuts through the bull and tackles real problems directly.

He knew half way through that he wasn't going to fit in with the culture. It was an all day interview where everybody was given chances to grill him. He was criticized as being wrong for not following very dogmatic principles to the letter of the law. He was also concerned that nobody really seemed to care much about his relevant business experience and really only judged him intensely on his programming skills, which he felt was only one aspect of his software development experience. It was an open floor plan where everybody wore jeans, t-shirts and sandals. The vast majority were in their early 20's with the oldest person and lead developer being 30. They expected him to be involved in side projects and code for fun when he wasn't in the office.

At one point when he was asked to move to another conference room he decided he had enough and said that he was done with the interview and wanted to leave. The room was apparently shocked and dismayed. He politely asked where the elevator was, at which point somebody snapped the answer at him pretty harshly. He could feel sudden hostility from everybody in the room at the time.

When he went to leave the lead jumped into the elevator with him and asked him why he didn't want to continue and he had said that he felt he was inherently at odds with the culture there and that he wouldn't fit in well. The lead apparently acted completely incredulous to the concept that any developer wouldn't be happy at this environment.

I am confused by this because a while ago I had left an interview early as well when I was without a doubt certain that I wouldn't fit well and the interviewers acted in much the same way as my friend described, incredulous and hostile.

Is this behavior considered inherently rude on the interviewee's part?

If anything I would guess that you are doing them a favor by not wasting any more of their time than necessary but maybe I am wrong?