There no exceptions, only holes.

That’s just a higher level variation of the normal mirelurk king. Just like an albino deathclaw is a higher level variation of the normal one. Also the mirelurk deep kings stats on the wiki are still lower than the queens.

Maybe I’m having a mandela effect moment but I don’t remember a “way bigger, way harder to kill” mirelurk king after the queen. The mirelurk king in-game is the size of a deathclaw tops and I think it’s stats are definitely weaker when compared to the queens. Is there a special one that spawns after the queen that I am forgetting?

Yeah, fun should always come before realism. If you can do fun and realism then do both otherwise do fun. Unfortunately realismcucks are a very loud minority.