Yuck! This is not great. I had enough bad experiences in my racing career with poorly machined parts to know this could cause trouble. There could be too much shear stress on one 6mm bolt that receives all the braking force. Keep an eye on these bolts to make sure they stay tight.
I agree that if the screw head interferes with the c'bore such that more of the screw tightening torque goes to overcoming the head rubbing on the rotor c'bore friction, less torque will be applied to clamping the rotor to the hub. To your point, the screw would be "loose". I properly designed bolted joint has enough screw clamping force to hold the rotor in place without it moving. Once that rotor starts to move, bad things can happen. I tightened up those screws and will keep an eye on them.
