Seems like a strange time to amnesty him. Unless they make further moves they will still play the luxury tax this year.
The Lakers have four amnesty-elible players: MWP, Kobe, Gasol, Steve Blake. All four of them are on expiring contracts. You can amnesty MWP, amnesty someone else, or not amnesty anyone at all.
They'll still be paying the luxury tax, but they'll be paying a lot less. As in tens of millions less.