I think if the position has already passed in the game, i think figuring out what move would have been better is fine, because they can't change their previous moves (if that's what you mean).
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)