Of course, we could just interpret the wish as "destroy Cauldron's base." Can't return to a place that doesn't exist.
We could go troll WH40K. At least that place pretty much deserves it. Lol.
I don't see a problem with this wish."Grail-kun!" The girl began.
"Taylor, don't!" The wife, Annette shouted.
"Wait, remember the Moon broke!" Daniel screamed in terror.
"-I wish you would go away and never come back!" she finished speaking before Matthew could take a single step.
"What do you want Abbadon-kun?"
"What do you want Asdrubael Vect-san?"
"What do you want Tyranid Hivemind-chan?"
Any of their wishes would be APOCALYPTIC on a horrific scale.
About the only safe thing to grant a wish to would be an Ork.
"Me wantz a gud fighty fightz with the humies!"
"You're hopeless, Taylor-san!"Obviously, the thing Grail-kun is going away from and never coming back to is the specific world that Cauldron-base is on. Earth-Bet is still fair game. Let's leave them with that one planet, so that they have a refuge after all the wishes ruin every other Earth in Worm.