Interviewing your line manager?

We are about to start interviewing for a new team lead. This person will be my line manager. I asked the “Head Of” if I can be part of the interview process to make sure this person meets the technical requirements and he said it was inappropriate for someone to interview their boss!

That means that nobody with any real technical qualifications is going to evaluate the skill level of this new hire.

Is this crazy or just me? I can’t help but think that it’s related to the fact that he was hired without any input from his team and is way under qualified technically.