Plenty of advice that is pertinent. I think you son's reason to fly, as you stated, is to become a commercial pilot and see the world. Well why does he want to become a commercial pilot. Appears to be a bit of a romantic notion. Mind you I loved the idea of air travel as a very young bloke but after a few trips to England the shine wore off very quickly. I dare say it is the same with the attraction of flying and after the first few years the shine dulls. Also the initial attraction of staying at "5" (prob 2 now) star hotels with a bunch of attractive people also loses it's shine.
If he wants to see the world there are other careers that will be more secure with less of an arduous path (unless you are well enough to pay all up front) and pay more which will allow him to fly wherever he wants. If he wants to be a pilot, well as kghfg said, there is a reason that a lot of commercial pilots have there own or part share in an aircraft that does not have auto pilot. Going the military pathway will provide a reasonable amount of hack rack and zoom even if it is only during training with the added bonus of no out of pocket cost but some time cost.
He really needs to be sure of why he wants to be a commercial pilot. Is it a romantic notion and if so he need's to take a hard look at the reality of this career.