No flips for you!
Clearly you've chosen to continue to engage, and do so with a silly strawman that says you have to bring this up immediately, interrupting the game, and that I'm recommending doing so for any level of disagreement. Please stop this stupid.There is a spectrum. Treating every frustration like it is a dire circumstance is problematic for the reasons I have addressed. You're not recognizing the difference. Look at the initial post again. Really read what the player is saying.
There is nothing in it that indicates to me that it can't be addressed completely and satisfactorily within the game in a way that is good for everyone. My guidance to that player is to attempt to do so. Talk it out in character and see what happens.
The OP is clearly upset enough to come to strangers to ask for advice. This isn't a trivial or small matter, or a whim. It's enough that the OP is thinking about it between games and wants the behavior to stop. This is prime material for a before the game discussion, which is what I recommended.
So, again, if all you have is insisting that the game be protected first and a string of strawmen, please do not engage with me again.