Charge or no call

[iref4him]

A fellow referee ask me the following:

"A1 breaks away from B1 and is driving to the basket. (He made his move around the division line.) B2 is not paying attention to what is going on, had his back to A1, and is standing. As A1 is driving, he collides into B1. WHat would you call?"

He told me that this actually happened and the official called A1 charging since B2 had the right to the spot on the floor and was there before A1. I would have gone with a No Call. Any thoughts.