I am just worried about the law.
It may be all grey area otherwise, but it is very clear about underage and gambling.
I have absolutely no doubt that young people can do anything us old folks can – I was on my own two feet running a business when I was 16 myself. Being 16 and female – lol – people laughed at me until they saw the results. Discrimination was thriving back then, being young was bad but being female was impossible then. The only way people could imagine a young girl making money was by selling her body.
If he is partnering with an adult, you could deal with the adult and avoid possible legal problems.