It would be in his best interest most likely. Jazz can pay him more for a 1 year deal than anyone else will. Unless he gets a really good offer it's more likely he can get a bigger contract in a future year.Favor's isn't signing a one year deal with Utah - it's probably literally his last resort if he faces a bone dry market.
He just went through a contract year where he played healthy virtually wire to wire and showed good life/production in the playoffs - he's not going to want to do that again. Hell, I'm not even sure he CAN do that again.