There was actually a law about 25-30 years ago that a Thai new born must have a Thai name only (the official name. Nickname could be anything). Back then some district offices were very strict about it whereas other districts didn't care and would register anything you wanted. I'm not sure if the law was removed or just mostly ignored these days.
As for Jason young - he was born in 1980, about 10 years before that law was introduced...