I've read elsewhere that the professor had a rule that you should not write a paper about anything illegal. That was because during the 1960s at least one idiot

I've read elsewhere that the professor had a rule that you should not write a paper about anything illegal. That was because during the 1960s at least one idiot wrote a paper like "I'm gonna start a marijuana farm and make millions!!!!!!" So the professor had a rule, no papers about starting marijuana farms, or any other illegal idea. The FedEx that became successful in the 1970s was borderline illegal a few years earlier. Regulations were reduced during the 1970s and then finally phased out when President Jimmy Carter deregulated the transportation industry in 1980. So Fred Smith's idea was in the same category as starting a marijuana farm. Both ideas faced hostile governmental overview. This is indirectly acknowledged in the quote from Esquire: "His skeptical professor didn’t think such a business had a ghost of a chance, considering the airline industry’s intense competition and heavy regulation." Right, in the 1960s the idea would have been very difficult, but regulations changed a during the 1970s and largely ended in 1980. FedEx's big success in the 1970s and 1980s was made possible thanks to the change in regulations.