Pssh. Who can't create pocket universes? Lame.

[But, since he did actually reply for something uncharacteristically close to an actual valid reason:]

Wouldn't get your hopes up, pal. I oughtta be able to bust us outta here, and I'm not the only one or the most powerful here who could tick that box, and... well, we're all still here. Don't let me rain on your parade, but, uh, don't throw that parade on a cloudy day and expect to stay dry, either.

[...this might have gone better if he hadn't stretched that metaphor so far, but whatever.]