First, if the sleeve spins freely, the plates will not be spinning when you unrack the bar, because they have stabilized between the time you load them and the time you unrack the set. Second, the sleeve is designed to spin so that the rotational momentum of any plate movement is not transmitted to the bar itself. This is the reason for the design. I think you are using a shitty bar with frozen bearings or bushings. Lube it.