It's good to see that he is going back to his roots. Malay were Buddhist before Arabs came and turned them into Islamic zombie terrorists.
The budhist Sri vijaya was overwhelmed by Hindu raja chola. So it's not Islam that exterminated budhism.
In fact, rfugess budhist fleeing india turned two empires. Sri Lanka and Sri vijaya after they were defeated in india.raja chola went after Sri vijaya as they controlled and collect taxes from trading ships in malacca straits.( dunno what it was called then as this was before malacca era)
So india was trading with the far East very early on. And malacca straits a very strategic and vital trading route even then.
At that time, there were no Thailand. The thais migrated southwards later or about this period. Came into contact with sri vijaya and became buddhist just like the khmers.
The chams who are ethnic malays in Vietnam retain Hinduism.
Eventually, all Hindu areas became muslims.