He is for sure too old to compete in MMA at any serious level beyond local organisations if he's 29 and hasn't been training full time
I did check and apparently he was an MMA prospect pre league, so he might do okay on the regional scene if he goes back to training full time
If his walk around weight is 210, he probably has to cut to at least middleweight to fight in MMA and 5'11 is very short for a middleweight
If he dropped some weight he might be able to be a welterweight and a big one for the division but those guys are so much faster than him and it would be a big weight cut.
If he was a heavyweight age and speed would matter a little less but at his size he's going to have to be an excellent martial artist to even succeed on the local scene.
He's probably better off doing the garbage celebrity boxing cards Asofa-Solomona and co do I think to pay the bills because low level MMA does not pay well and he is probably sub 1% to make it to UFC level and even then the unranked fighters don't get paid, i'd imagine even at PFL/One level etc he is getting massacred. He probably has to make it to the UFC, PFL or One FC in order to be making even remotely similar money to what he'd make beating up part time plumbers from Rockhampton on Australian boxing card of the week featuring Paul Gallen and friends
I'd love to see him do well but it's a tough transition to the elite level of MMA outside of heavyweight which is a thinner division due to there being so few A level athletes that are that big and choose MMA. As far as I can tell though he hasn't even done any amateur fights yet in MMA so being competitive on the pro scene is going to be at least a few years away if he is extremely naturally talented and works hard and at that point he starts ageing out of his prime slowly
Boxing would make so much more sense for him because people will watch to pay him crush cans on Australian cards or fight other ex NRL guys etc
It would be epic if he managed to go on a run in the UFC or a major MMA org though and I hope he manages to do that but it's a very very long shot