The more I think about it....

[HateSolstice]

I always just assumed that Alexander was driven by both his desire to get the hell out of here and by the desires of the orbs. He was becoming desperate, as evidenced by his reactions to Daniel contacting him. Plus, he'd been here for centuries with no end in sight. I really don't see it as him being a man-child so much as he's much more than a mere human, and just sees us as cattle.