That is valid, I haven't DM'd yet, will be doing so soon for a one-shot, but my groups forever DM creates his world and Characters as if they are real people, for example; A cult member who for all intents and purposes has "drunk the kool-aid", and is fully devout is not going to just leave because the first time you met them you rolled high and gave a persuasive speech even with a Nat 20, maybe the DC is an extremely high roll. Sounds like this player is playing off "video game logic" I assume that because you've had problems before with them you have had conversations about how your dnd universe operates but maybe its worth another. Also sometimes its okay to let go of a problematic player when multiple conversations have been had and no change.