Sonic half wishes Donnie would have asked him to stay if only to exist in the same space as Eggman out of pure spite, but also he doesn't want to exist in the same space as Eggman at all right now. Especially after that fakey fake concern, which Sonic finds far less scary than he does infuriating. It's a reminder of what maybe could have been, if Starline hadn't butted in and reminded Eggman that he was a giant douchebag. It made Sonic just feel bitter about it all over again, and between that, the way his leg is throbbing, and his general annoyance with this situation and with himself, yyeeahhhh he's had enough.

He refrains from telling Eggman just where he can shove those Coconuts sentries, and waves over his shoulder as he heads for the door.

"I'll manage. Don't let him talk you into any wild world domination plots, Donnie."