I don't know anything about him really so can't comment on that.
I wouldn't put so much weight on trying to define every non thai fighter though. There are so many variables like how many fights one has had in different rulesets, his style of fighting, his trainers, history, fighting philosophy background, identity etc. In many ways the japanese kickboxers are probably closer to nak muay than many guys in lion fight or fights in europe that don't use elbows or have inconsistent scoring.
If promotion A in japan considers themselves muay thai and promotion B considers themselves Japanese kickboxing, but in practise the fights are ruled and scored the same, why would it matter so much?