I'm not sure what the rule is there. Is it interference because you can't touch it on the way down, or because it's in the cylinder? If it's the former, ISTM that'd rule out many alley-oops.
I think the point is that you cannot "help" it in if the ball is in the "cylinder" above the hoop. If a defender touched the ball there, it would be goaltending, whether it was going in or not. So the offensive player can't touch it in, either.