a. It was bought on-campus.
b. If he stopped all donut services because of one guy who looked unhealthy, then it again shows how capricious he was. One person who looked a little unhealthy ate a donut on one occasion and he removed donuts from every single store on campus for every single person for no reason other than he didn't like to see someone who looked pasty and obese walking around eating a donut.
Because that's the sort of guy Steve Jobs was. A sociopath.