Mateus always struck me as an extreme narcissist, I mean he basically wants to conquer the world in FFII because he feels its his right to do so. I can easily transpire that as him wanting to replace a "god" in the Dissidia universe. I read an interesting tidbit from a fan translation of the Ultimania that said his goal was actually more thought out than the game lets on. (Its amusing to read at least). So I still feel the man is pretty damn ruthless and an excellent mastermind.