At first I thought it was a bolt going through a shaft, but after a closer look, it does seems to be a solid shaft with a 6mm hex socket head. A couple of O-rings stops oil from getting to the plug located on the cover. That shaft does not seem to serve any purpose whatsoever ... so what's it doing there?
Any idea why the cover bolt allows access to the 6mm hex head on the end of the shaft? Is there maybe some sort of adjustment factory techs have to perform prior to certifying the engine as properly counter-balanced?