I think the fact that it's a nod to "Army of Darkness"'s nod to "The Day the Earth Stood Still" takes precedence over plotline considerations. It's a joke, and I don't think it relates to the plot any more than the "mad deadly Frankenstein computer god" bit. ;)
That said, the fact that he recovered so quickly and was able to whip up a teleportation spell is a bit strange. But possibly he was able to set up some powerful healing and teleportation spells before he went into his coma, which would be triggered as soon as a power source (like his staff) was brought into his vicinity.
--SiliconDream
