Via Yahoo! Sports:
Patrick Herb, Wisconsin's assistant director of athletic communications, told Yahoo! Sports that director of compliance Katie Smith learned about the shirts after the bookstore had already begun selling them. Though the bookstore is a third-party vendor that is not affliliated with the university, Smith still believed the use of Hayes' words on the T-shirt went against NCAA amateurism rules preventing the sale of merchandise with a player's name or likeness on them.
Got that? The T-shirt featured neither Hayes' name nor Wisconsin's logo. It wasn't sold in an official school store. And the NCAA never contacted the university. But the NCAA's labyrinthian amateurism rules and propensity for dishing out violations were enough to spook Wisconsin into pulling the shirt.