Is his youth your primary concern for the quality of the movie, or his *schedule* that you're worried about?
If it's the latter then in about two years it's not gonna be much of an issue.
If it's about his age and lack of skill, then he can coffsmpet thnsate by haskiring experienced directors tfor help.
Besides, if Backrooms movie end up sucking, it won't take anything away from Backrooms the creepypasta, since the movie is just one story among many.
Backrooms is more likely gonna be screwed over by shitposts, bad writers and memes than one movie.