Professors everywhere (even at Duke!) allow student-athletes to push back deadlines based on games, tournaments, etc. This isn't unusual.
That said, he clearly makes a mockery of being a student. Not really his fault though, the system is broken. The #1 option for amateur players after HS is to go to college b/c they can't go pro, even if they have no interest in being in school. Sure you can go to Europe or I think even the NBDL (??) but the best competition, the best place to learn, the best option if you want to get drafted into the NBA, is to play in college.