Re: So... is he an engineer?
After thinking...the issue seems to be: does the state in question regulate the design of electronic equipment, including circuitry not offered for retail sale, and, if so, does it require the engineers who do this work to be licensed professionals? I do not know of any state in which this is true.
In my state, the answer is "no". However, people who run businesses which repair radios, televisions (and, perhaps, microwaves and washing machines) ARE required to be licensed. This seems to be more about controlling the number of such shops (to keep prices high) but with an avowed purpose of keeping said shops honest for consumers' benefit (in reality, the repair is done at an outrageous cost, and if it fails in a week, tough). The licensing fees are also a revenue source for the state, and the agency provides full employment for those who might be politically connected.
In the EE design world of which I am familiar, safety and quality are tested by independent agencies like Intertek and TUV. You're free to design things that are not tested, but offering them for sale would be risky, as proof or certification of testing is required in many cases (UL or equivalent for things plugged into the mains, FCC for things that use or radiate RF, etc).
My coat's the one with random components rattling around in the pocket