I'd say, let him finish the program in mechanics ofcourse. It's nice to have a backup incase airlines don't work out. Check around to see if your son will reach an age requirement (and holds a working permit or permanent resident for that country if required) for an airline cadet program (they pay for all the training). If there isn't and he wants to get his private and commercial license, I suggest going to Canada or USA for flight training as it is cheaper, especially since most airports here don't have landing fees.
If you do find a cadet program he will be soon able to apply for. I'd suggest doing a cat. 1 medical exam to make sure he can atleast become a commercial pilot and then get him into some basic flight training, atleast up until he goes solo once. It would be a lot easier during flight grading since he has to demonstrate that he can learn very fast. And if he doesn't get in the first year, not to worry, most people don't. The fact that he'd have a diploma in an aviation related course would mean he could still be working within the industry while he waits to apply again.
He's still young, lots of time.