That’s why you need experienced hiring managers. The questions should be discussed and approved before the interview. You just don’t let an engineer ask whatever they want. An interview plan needs to be shared to avoid overlapping questions or topics between interviews. In this particular example the hiring leader did the right thing, only after doing the wrong thing: not review or having an interview plan discussed beforehand and training the interviewers. The interviewing principles need to be clear to all your interviewers.