This is a JK freedom panel. This piece here rotates down to run just the freedom panels to keep them tight, otherwise if you don’t there will be play after you screw the locks in because they are just a bit long.
A lot of people don’t even know about this spacer even after years of ownership.
Yeah to me unlocking the freedom panels and sliding forward is not the same as keeping them on while only removing the rear portion of the top. So you can’t remove the rear portion without some type of moving the freedom panels. Whether you slide them forward or remove them it has to be done to remove the rear.You don't have to remove the panels to take the top off. They only have to be unlocked to slide them forward a bit for clearance. It can be argued that unlocking is the same as removing, but I've kept them on loosely to remove the top. I don't know what you mean by a 'rotating spacer,' but it's possible to keep the freedom panels on without the top without any vibration. There's nothing other than the locking tabs.