Riley has coached future pro qb's. Mannion went pro after a losing OrSU season. If the Gebbias only care about a possible pro spot, then team results don't really matter. Add that TLee looked bad and the staff stuck with him.
So if I was a Gebbia, I could see Tristan as the heir apparent after TLee leaves. The lone Riley QB that will get nearly all the snaps from anointed starter until leaving the program. Independent of how well or poorly he performs, he would be the guy being prepped for the pros.
Unfortunately for Gebbia, more people care about NU's record than about a qb's pro stock.