I know it should have been in the writing menu, but I even looked through the entire computer menu too, and it wasn't anywhere. I did decide to cancel it after I posted. Writing is only his hobby. His career is in medicine. He had the biography opportunity for almost a whole sim week before I tried to have him do it, because it was more important for him to bring up his logic skill to the level he needed for his career level. So maybe that was it?
I might try giving it back to him later, when I can have him get to it without so much delay. He is getting called in for emergencies so much, I don't think I'm going to make him stay in the medical career until retirement. Writing books is one of the potential second careers I'm considering for him.