MMA's a little different to MuayThai in the stadiums and pro Boxing. Legal age to turn pro is 18 and most start a lot older. There's a UFC LHW contender called Jimi Manuwa who doesn't live to far from me. He started training and competing at 27 with no fight experience before that. He made his UFC debut at 33.
A lot of MMA guys come from one specific fighting sport and they're no longer prime in that sport but still manage to have success in MMA. When it comes to striking Nong O is 20 years ahead of everyone else and not just a regular 20 years. The highest of levels. He's also been at Evolve for a while now so probably knows a good amount of grappling. His career might not go any further than ONE FC but depending on how serious he is he very much could go further. Dejdamrong is 38 and still looks fit and healthy. Nong O will be 38 in 7 years. A lot can be done in that time.
But still Nong O is not ideal. Evolve need to bring in a young Thai.