I could use the same idea as Gohan during the Raditz arc, since Cello has no real idea on how to focus ki. 700 base, but 1300 when enraged, which is when he manifests his ki into a type of explosive wave?

Also, I would say he heard in passing from the slavers that some kind of crisis happened on Namek, but that he didn't hear any specifics. The main problem is he's flying the ship kind of blind. He understands the mechanics of it, but he isn't really knowledgeable about how the navigation system works. The idea was he'd just be flying the ship, and broadcasting a distress signal in hopes of someone picking him up.