make him a Lafayette/Gaffney type offer: prorated vet min this year + partially guaranteed 2nd year.
It might seem little money for Oden, but it's not very clear he'll be able to play this season (if ever, look at Brandon Roy). He can rehab as a Celtic, get a fresh start in Boston, and earn his payday in the 2014 summer while having a chance to win now and backup KG (and eventually replace him in the starting C spot someday).
The Celtics could end up losing some money, but little compared to the humongous reward a healthy Oden back in the NBA could be.
Probably he goes to South Beach to meet the Three Stooges and that guy from UConn. Sad.