If his experiment works out moderately well I could see a great consulting business in training and self-improvement. If it works out really well he is now a professional athlete which seems pretty cool too.
I really wonder how being an amateur golfer would change the 10,000 hours - would it be a head start or would it hold someone back?
In theory, it might be a detriment. The brain is fairly plastic (i.e., can be reshaped and rewired constantly), but reinforced behaviors get pretty firmly hardwired. This is why "old habits die hard," and "you can't teach an old dog new tricks." Quite literally, the neural pathways we use most frequently and automatically become the hardest to rewire.
Ergo, if you've learned the game up to a certain skill level -- and then coasted at that skill level for decades -- you're going to need to rewire significantly engrained neural pathways in order to relearn the game and break through your plateau.
It also helps to be able to start young. Not only do you have more time on your hands when you're younger, but you learn more quickly. Your brain is much more plastic in childhood. Interestingly, in most of the "10,000 hours" case studies I've seen, the subject started practicing as a young kid. It's entirely possible that the learning curve is steepened or elongated for people who start as adults. A child might be able to go from beginner to master in 10,000 hours, but an adult might need many times that number of hours.
I really wonder how being an amateur golfer would change the 10,000 hours - would it be a head start or would it hold someone back?