@Brandon ***********
IF (and only if!) he can get a re-entry permit on Immigration, he can return for the remainder of the initial 90-days stay permit.
But since he said that the internship will be terminated before the 90-days stay permit expires, then Immigration must be notified about that. And this will - most probably - void his chance to buy a re-entry permit. Or can you buy a re-entry permit for a remaining stay permit when the reason it was issued for, already got terminated?