In fact, I can't help but like Taravingian. Here's a guy who believes in the Almighty, as evidenced by his debate with Jasnah early in the book, knows he's completely dooming himself by his actions to whatever doom these guys believe in, and yet continues his actions because he believes his saving the world. And for all we know, he might be right with what he's doing. He calls these people his dear friends, and is still willing to sacrifice them. Evil? Completely. But he might be just what the world needs at this point.
Yeah, I would much prefer a Taravingian book to a Shallan, Adolin, or another Kaladin book, but I don't think it's happening. Some characters need to remain mysterious.
Actually, I find that this makes Taravingian
even more disturbing, because he has been warned against this behaviour by an authority figure he clearly trusts but in his own self-aggrandizing arrogance thinks that ethics are for other people, not him, and he's got to do whatever it takes to win. He may have given up what he perceives as his ultimate reward, but by doing so he's undermined the whole foundation of what he believes in and no longer has a coherent philosophy to stand on. In short, he's not just a person going to monstrous lengths to do something that's probably good, he's also a hypocrite.