Oh, I see, I thought you meant it was hard-wired for context_id.
Still seems a bit odd to me. Since it only supports PG, it would be easy enough to say "average the ratings for all the child objects of child forum_id" when you want to display that, and cache the result if you're worried about performance.
Anyway, it's not a dotlrn or core package obviously, so you guys at UNED should just do what you want, right?
Since Oracle support obviously is not an issue for this package :)