Interesting, but I don't find David's line appalling or sickening, or the least bit inappropriate for a 10 year old boy.
As someone who has been a camp counselor to kids that age, I don't find it odd for a boy that age to make such a comment. I've heard lots worse but it would not be something I would think of putting into a movie script, but that's me.
including an interesting note about a character no one imagined would appear.
Apparently the scene I so widely object to is in the final cut of the film, which is unfortunate, because it has no place being in something called Dark Shadows, and imo destroys, perhaps, the most vital character relationship in series history.