I’ve had a fun fan theroy for a while, that the Peter Cushing Doctor is The Doctor of Pete’s World.
Suppose that at some point he stumbled across a galaxy in his universe ruled by an evil tyrant, and he realized there was no way he could stop the tyrant. There was a small resistance movement, which needed more support to succeed, the people were just too scared and complacent. He was unable to inspire more people to resist by working for this resistance movement.
So he manipulated his way into the hierarchy of this evil empire. Seeing no way to mitigate the brutality to any significant degree, he decided to bring it to 11 instead, in hopes that the peoples anger would overwhelm their fear and complacency.
The Doctor of Pete’s World eventually decided he had gone too far in pursuit of a greater good. Thus, he refused to escape when he had the chance, and “Grand Moff Tarkin” met his final death on the Death Star as it approached Yavin IV.
This “theory” absolutely positively should not be taken seriously.