Rod1
You have explained the rules but that is a circular argument.
"I cannot drive up the M1 at more than 70 because the speed limit is 70...."
Am I right in suspecting the real reason for prohibiting "mass production" in the non-CofA scene is to limit the level of activity and thus support CAA CofA revenue?
I cannot see a rational argument as to why a flying machine like this cannot be factory built.
There is an argument that somebody who built his own plane is more entitled to kill himself in it than somebody who bought it from a factory, but that is a bit stretched. We all have a fundamental right to kill ourselves (accidentally) - otherwise there would be no mountain climbing, scuba diving, driving, walking, etc.