Question about play to win rule…

I observed on many tournaments players in 2 player game just shaking hands and finishing game early by one player giving up.

Sometimes this was result of an in-game deal, which although not enforceable, a player decided to honor the deal and give up (eg player got promised VP in 3 player game and then just shakes hand with the player that helped him instead still battling it out).

I recently had a debate with a player who told me such play is only acceptable under the play to win rule, if the player that gave up didn’t had any chance scoreing GW.

Is this correct? Is this a situation where observer should call the judge even though both players agreed? Is the play to win rule in such situation violated?

More generally under what game conditions should judge prevent one player from giving up?

When you have already won the game you are not enforced to try to get even more VPs.

So instead of just, say, on every turn hunting with all minions and transferring out as many pool as possible you just yield. This way the person who (probably) helped you to get the GW gets their victory points (2 or less -you could also consider this to be 30 pieces of silver...)

Granted, there are situations where the amount of pool and/or lack of pool damage combined with short time left might make the actual ousting, even with above style co-operation, impossible.