>>23569812
Without defending the Rozen Zulu, the actual claw actuators are likely behind the actual "wrist/palm" where the beam guns are. Because of the arrangement, the center would indeed be hollow enough for the guns. While difficult to see in the OP image, you can also see, if you look closely at the rightmost finger of the Rozen Zulu, a sort of black amorphous bit between the iron nail and actual cannon housing; presumably this is the body of the finger connecting it to the arm and the actuators inside of it.
Overall this isn't particularly uncommon as a mecha design trope and can be seen across a variety of designs such as the Z'Gok, though the Z'Gok only has one beam gun in the center of its claws and IMO executes the idea much more gracefully.
