Grand Moff: the burden of proof still lies on the person advocating for the Palpatine-act to establish that he had the foresight to magically know that Windu wouldn't just lunge in and cut his head off.
How could he know that?
Again, you're suggesting that Palpatine was not stupid, but rather arrogant in his foresight, suggesting that he foresaw how Windu would act. That would be a degree of Force sense he has never replicated. He wasn't even aware of Skywalker's presence on Endor.
Intrepid: you respond to my primary contention by pointing out that Palpatine could have killed Windu early on in the duel. Firstly, you may or may not be correct, since it appears that Windu was able to deflect his stab, and it's not as if he couldn't have done so earlier. Secondly, it does nothing to address my contention that Windu could have also killed him easily after kicking his saber.