May sound like a stupid question; but it is

It pivots on the mounting bolt. The idler arm should not turn on the bushing itself.
My Moog replacement has a grease fitting in the side.......Adding grease does not make it to the bolt hole. At 65lbs, I would think that the idler tube would be squeezed between the K frame tabs. I have zero up and down movement once I install the idler and the corresponding washer on the lower side, and torque to spec. It works well.

Also....When I clamp the tube lengthwise in a vise, the unit moves on the bushing.

I am confused.....