Obviously I don't know you or this guy so I'm not trying to dispute your story, but I'd like to point out people get nervous with these things, or misunderstand the question.

I got a friend of mine an interview at a BigCo I used to work at. Since he was already a friend, I wasn't allowed to be part of the interview as that might be a conflict of interest, but I did see the review that the interviewer wrote, which said that he didn't know what a for loop was.

Now I had done several projects with this friend, he was someone that I knew was quite competent at coding (and I had seen him write multiple for loops in the process). After he was already declined I did kind of ask about it and he explained that he was asking a clarifying question about how many times something needed to be repeated, they didn't directly answer, so he assumed that that meant "potentially forever" so he did a while loop with a break condition. The interviewer had taken this to mean that he didn't know how to do a for loop.

Now it's possible that my friend was lying to me, but again I had previously seen him write lots of code and I knew he was smart and able to do that, so I'm inclined to believe him.