The whole 'like a shark' thing suggests that Xander can't stop moving, or he dies. So, 'spinning gold' from this crappy situation, Giles gives him a field position, where his constantly being on the move becomes a feature, instead of a bug.

D'Hoffryn has something to do with it, and, knowing Xander, I'll bet 200 quatloo, it isn't *Xander* who dies if he attempts to settle down, it's people around him who will suffer...

Wouldn't that be a vengeancy-thing? 'You wouldn't settle down with Anyanka, I'll make sure you don't settle down with *anyone...*'