I'm thinking the Celtics want to trade up in the draft. They'd probably be willing to S&T Rozier if it facilitates going up in the draft. I don't think T-Roz is a starting PG for the Celtics because he can't shoot and neither can Smart. Putting two non-shooters at the guard position is suicidal for the offensive output.
So I'm passing on Rozier coming back. Although at 8m per year, which I doubt he signs, his contract becomes bargain basement value which we can flip later. But I honestly don't think he accepts that offer.