Somebody else asked this a while back, and it was suggested (as a joke) that he get the handle & grommet wet and let 'em rust together. I've got one that is rusted up like that, and it definately does not spin!

It also definately will not come apart!

I'm not suggesting you intentionally rust your stick, but you might shoot some glue in between the grommet and handle. Don't use anything really strong, or you won't ever thet the thing apart again, but if you use some cheap glue that you could break the bond if you pulled hard enough, that might do the job.