Are you 100% sure the primo is actually primo and not something else? It could be a long acting testosterone so he could actualy be shooting 500mg of test for which those blood levels make sense.
I already addressed this. 600 mgs of test would raise levels much higher. Now if it was a mixture of primo and low dosed test, that's possible. It's be hard to tell, though it may be more trouble than it's worth to the UG, which has a good reputation.
This is the thing with this stuff, we always have to leave the door open to possibilities and never draw any "absolute conclusions."