Report this listing now. I know it seems petty and stupid but it is unfair that this guy can violate so many rules and regs. It is unfair that he can unfairly and illegally compete against reputable tester manufacturers.
Most important...it is unfair that he can put other peoples lives and property at risk to make a buck.
If I was contracting illegally or violating NEC rules I would hope someone would report me. It is OK to put yourself at risk. It is not ok to put others and their property at risk.
Do you suppose this character doesn't realize what a dangerous item he is selling? Not that that excuses him.
I once saw an RV that belonged to an MRI and radiology outfit. They had a gimmicked up attachment like this, connecting the mobile unit to the building. The plugs on the RV end were half-melted, as was the insulation on the cords to the plugs.