Moving the planet is surely out of budget. When he swiped Oisiri, that was remarked as a really rather incredibly large expenditure.I'll add my voice to the chorus wondering why Petey didn't just teraport everyone away physically, or even the entire planet. I mean, it seems like he might do that anyway since he clearly expects the planet to survive the shockwave.
EDIT: Okay, a story thought: we know at least some of the exogalactics fled in organic form, not as infomorphs. They're probably not going to be cool with what Petey just did at all, should they hear of it. The whole setup for him 'needing' to do it was a result of deciding to blow the (energy) budget on making contact with the exogalactics. I predict this will be observed for irony at some point.
Also, Petey being smug about making serious moral compromises has all the hallmarks of the AI-who-would-be-god heading for some comeuppance. Unfortunately, delivering that is prone to involve considerable collateral damage.