Hemi oil pump priming tool from Summit

How in the he'll does that work?!! How can the pump turn when it is engaged on the lower crank gear of the timing set?!!!! The lower timing gear is what drives the pump.
Aftermarket timing sets come with a separate cog that only drives the oil pump. The lower timing gear does not have the pump drive attached to it.
I forgot that the OEM ones are like what you described.