I feel like Stone, regardless of whether or not he commits, is a big recruit for this class. If we end up signing him: (1) Kiffin backs up the "fence around TN" rhetoric, (2) Kiffin and co. continue to fill the need at OL by adding a versatile, skilled, highly rated player and (3), a positive statement is made to other offensive recruits that consequently has a luring effect.
If we don't: (1) losing Marlon Brown, (most likely) Barry Brunetti, and Stone would undermine Kiffin's assertion about the Recruiting Fence. We become less convinced that the staff can hold on to talented kids from TN. (2) We inexplicably lose out on another big-time player, to a rival, with whom it seemed we had a very good chance of landing. (3) we have to move down our target list.
I don't believe in "must gets", but I think Stone should be a big priority for Kiffin.