It feels like a motte and balley because you're getting confused about what his question was. You seem to think his question was whether a malicious actor can p

It feels like a motte and balley because you're getting confused about what his question was. You seem to think his question was whether a malicious actor can pretend to be incompetent. That wasn't his original question. That was the situation he presented later when asking me for more detail. The existence of that claim doesn't have any bearing on his actual question. It shows an instance in which the union of the two sets isn't the empty set not that the two sets are equal. There exists a disjoint. Therefore they are not equal. QED. However, for the purposes of debate lets say we strictly limit our discussion to the cases in which there is malice. We're now in a competitive context in which our upside is going to be minimized. A lot of people don't seem to realize that the prisoner dillema is actually a condemnation of rational behavior, since it traps us in the worst possible world. It's actually smarter in plenty of real world scenarios to intentionally cooperate, sacrificing your own utility, rather than engaging in tit for tat. Flowing out from this mathematical idea are many teachings in religion from the Lord Jesus Christ like being good to those who are evil to you. You can see the underlying principle in our biology too. We aren't strictly rational, we instead have emotions. In particular people who are angry with other people have health consequences. There is a biological punishment to choosing not to cooperate built into us. This shows that evolution has selected for that quality which implies there is a benefit to this. I say all this because not attributing to malice what is better explained by stupidity isn't a completely foolish idea even in the case that they actually were malicious. The world in which they merely pretended to be incompetent is less severe than the nuclear war of tit for tat that wipes out all life on Earth and leaves it an irradiated wasteland.