As sad as it to waste what was probably perfectly good food, they have to do this.
If this employee got sick off of it, Starbucks could get hit with a workers comp claim because workers comp is a no fault (meaning even if you are stupidly doing something, and get hurt, they still pay) type of policy and after so many of these claims, the policy would increase due to their claim rating.
It works both ways. I had a finger amputated several years ago, while working on a machine that had no finger guard. After my finger was amputated, the company put a guard on the machine.
Limited liability for the company.