ISTR McCoy described him as a passionate Vulcan. And I kind of imagined that passion would be negatively targeted against Romulans, for being capable of doing what happened to Vulcan (we can only imagine the diplomatic complications between the Federation, the remaining off-world Vulcans, and the Romulan empire). I also figured that not all Vulcans took the destruction of their homeworld very well, and shake the faith of some. Sybok's an opportunist, and I kind of see him as capable of taking advantage of Vulcans who can't cope with the raw feelings that come out of that cataclysm. Even if there turns out to be a different explanation, Sybok is an interesting character worth exploring (I don't hate Final Frontier, it's an okay movie). I would read a book or comic in the alternate reality about him (although I figure it's not super likely, story editors probably would feel he's a financial risk not worth taking).
