Jiro isn't very smart in the grand scheme of things, and he gives no thought to where an apple came from or how irradiated it may or may not be. What he does pick up on is Sandy's continued annoying faces.

"Don't look at me like that, you little shit. I saved your ass and your fucking robot!"

He is not above picking a fight with a 10 year old, which is what he presumes Sandy to be.