I wouldn't pay much attention to 'his' qrz logbook as only a small % use it, the entries could easily be those who have uploaded their qso's with him, therefore appear in his logbook.
I suspect the MI3 was the subject of a wind-up, rather than making it up, and that it took place on the amateur bands. Career foundation licence holders tend not to be the brightest lamps in the street, the exam is easily passed by young children. the M3 prefix was used up some years ago, and M6 has been issued since 2008 for foundation licnces. He has been stuck on the bottom rung of the ladder for a long time.
Failing that, just some mix up with a /AM operator on the amateur bands, they do exist but not in the numbers there used to be.