They’re supposed to rotate…
That’s how they keep people from stealing balltop handles so easily in arcades.
If the shaft cover didn’t rotate, the thief could hold the shaft and screw the balltop easily.
Someone told me that’s a good reason for why Asian arcade managers generally don’t put “bling” balltops on control levers like the LS-32 which doesn’t have a shaft cover. A bare shaft can be grabbed and as long as the perp’s hands aren’t sweaty can be used as a lever to make it easier to screw the balltop handle off. My personal experience is that it’s still a bear to unscrew a secured balltop off an LS-32 shaft even if it doesn’t have a cover. I still need to lift up the faceplate and use a screwdriver to take off the balltop!