This point is debatable.
Episode Recap:

Grant is getting more and more annoyed at the whole situation, apparently Xander is powerful enough to have rescued them with a thought without even getting up from the dinner table. Xander, meanwhile, has fun entrapping Grant with his own actions and simultaneously fixing the cracking veneer on Grant’s old Mercedes. Xander’s not just magic, he’s exceptionally magic. He hops out of the car into the rain, despite Grant’s protests of being like, old, and then insinuates that if Grant doesn’t pick up the pace he’ll kill the castaways or let them die or something and then they can just bury the bodies. Grant is horrified and chases Xander down the cliff, grabs Xander and tries to make him promise to save the castaways. Xander reflects for a moment, not on his physical ability to save them, but on a more subtle ability to set them off a path of destruction. He’s never been able to ‘save’ anybody, he says. Then he off and does a moses on the ocean. He’s also telekinetic. & stuff. Grant’s confidence in his abilities is not misplaced. Xander backs into the sea and vanishes as Grant watches from the beach.