Imagine destroying the earth is all an elaborate plan to: get Bub to outer space -> set him up with Karellen -> Make kids that have extraordinary processing power -> make said kids do your homework so you can become the 5th dimension man -> ???
Since the situation "looks bad", maybe he's gonna reset the Earth back to normal now? since the whole deal for this was to create the kids so he can do his 5th dimension man thing.
Since he can undo everything, that means that the whole space travel never happened? uh oh... (kids disappear? bub back to japan with a certain woman) also explains why karellen's death was so whimsical, so that kids travel with bub -> kids can "meet" him in a not-so-suspicious way.