Well, up to a point. I wonder how much all that mind control scrambled his brains

He's pretty unwell, even before he gets stuck in a pillar for 10 000 years, yes.
I have some sympathy for a Quest of Revenge when it comes to people who avtually wronged you (and Ye Zun seems rather convinced of Shen Wei's betrayal), but none for extending that to uninvolved third-parties.