It is. Personally, if the actress is 18 or older, she is allowed to act in an X-rated film. Period. That's the law. When we start getting into the "fictional representation of children" it becomes subjective. What exactly constitutes dressing like or looking like or "fictionally representing" a child?
However, in Max's films, no effort is spared to make his actresses appear as child-like as possible.
I suppose it's only a matter of time before 3D animation gets so good, you can see a video of any sick thing you can imagine. What to do then. How about a chillingly lifelike digital cartoon of child rape? It will happen. What then? Just a weird, weird area to get into.
I used to draw cartoons. One time I drew a pretty raunchy one that I thought was funny. It had a woman--let me try to be careful here--receiving a male sheep, who might have been acting like a dog, if you get my meaning. The caption read "Mary had a little lamb." Should I have gotten busted for beastiality?