I don't see the comparisons between Justin and Damonte, just two very different players in my opinion outside of a team first attitude and willingness to show effort on the court. It was fantastic seeing Justin have a good game against Rutgers, but from what we've seen thus far out I'd still have him in the deep sub category (3rd or 4th off the bench depending on foul situation) though if he starts stringing performances together like he did at Rutgers, he does have room to move up.
I do agree with your DGL take though- to get time he's going to have to earn it, and thus far he hasn't really done that in his opportunities. He'll get a few more chances, but it has always been difficult for freshman to break into the B10 and show themselves capable of playing anything outside of spot minutes in conference play without being bullied. Really, Griffiths of Rutgers is in similar shape right now though he's an even more dynamic a scorer. B10 upperclassmen will just go at you, pick you apart, and take your lunch money.