I don't like it. He could suffer injury or arthritis in his neck down the line. The neck is designed to hold up the head, not to be pushed down.

I have read that young soccer players should not bounce the ball off their heads for the same reasons. Similarly, it is not a good idea to do headstands. The principle is the same - it's not a good idea to push down on the neck.

Well-developed adult males might get away with bouncing the ball off their heads sometimes, but not children. With women, who knows?