He isn't totally wrong. The ones making the jump from HS to NBA prior to being 20 are about 99.9% black. It does come off as racist.
In other sports (NHL, Tennis, Golf,..etc) jumps like this are made all of the time. Christ, 14 year olds play in the US Open, Wimbldon, and French Open all of the time. But, the vast majority if not all of them in those sports are WHITE!
It's easy to brush off what O'Neal said as just some angry black man thinking his people are being held down again. But he actually has a very valid point.
And his argument about joining the army at 18 but not being able to play basketball for 48 minutes is so true!