Since the question I posed was about incorrect player knowledge backfiring in game, what you'd do as a DM does yet again not answer the question.
Sorry. I wasn't trying to be cheeky. You see, I only DM. I don't feel comfortable answering questions about the players' side of the table.
Basically, is there any line for you where a player exploiting knowledge their character hasn't learned from play a bad thing?
Nope. I don't police players. Period. I run the world. Players run their characters.