Simple. Although Whipple wasn't enrolled in summer school due to playing summer league ball in Kansas, he was expected to be enrolled in school in the fall, according to coach Robe. Thus, Whipple leaves the school/program via transfer. Even if a player quits a team and later transfers to play elsewhere, you could say he is "leaving" one school for another.
Again, Robe told me in all my conversations that Whipple was suspended, and I think I have a proven track record in providing correct information.
Here are a few other examples of similar situations across the country. Note the headlines:
BC quarterback Davis suspended, will transfer
Suspended NU player Incognito leaves school
Suspended player calls it quits at UNM
Ray Small suspended, will leave program