Order 66 raid character limitations makes no sense (partially)

Alright, so I was checking the characters needed for the raid. Now while Jedi being required makes sense, I don't understand the reason to allow Grand Moff Tarkin and Dark Side Clones (Dark side clones since they are essentially meant to form a vaders fist, and Tarkin since Moff Tarkin, from episode 4 by the way was not present nor had involvement in operation knightfall). You also have the pirates, but I don't see any reason what so ever for pirates to be there at all. It would make more sense to allow Jedi and light side clones, these including the bad batch/501st clones Rex, Echo, and Fives, and ARC trooper if we even allow clones at all.