I don't think the rule is literally that the hand is part of the ball - just the part of the hand that is on the ball. Heck, with the size of some of these guys hands you couldn't block their shots at all if the rule was more strict.
That's exactly the rule. And his hand was on the ball completely. Stupid rule, regardless, but it was a bad call (talking about the Kobe foul on Bonzi).