I doubt JB gives unconditional "guarantees". He's been around too long for that. But we all know that he's very loyal to elite guys he brings in. DC2 has started (virtually) every game when healthy. JB's done this with other high level recruits. If they don't perform, he subs someone in (if he has a sub). There's no greater assurance a player can ask for ... no one, guarantee or not, is going to play if he can't check his guy and/or can't hit the backboard.
Obviously, the 3's wide open at SU with no one in direct competition. Without White, JB would have to rotate TB there (undersized) or TL (oversized). It's ideal for White's game. He knows we need a wing shooter and defender/rebounder on the baseline on D, and that if he comes in we have all the pieces for another FF run (maybe better). I don't see how fussing over "guarantees" changes any of that. He can shoot. We need him. He'll very likely start. Get your gear and get in the car.