I understand that that is kind of a taboo thing to do. It's like an unwritten rule and it makes sense.

But if we just keep that aside for a millisecond, doesn't he have a valid point in a way? Isn't it reputational suicide these days to question the popular narrative in many regards? (And yes, let the downvotes roll in, thereby proving my point :))

Every society has its reputational killing taboos. That doesn't make a methodology based on doubting everything invalid. I mean, what if incest was a good thing?