Just remember that Sage told MC during the party that she swithed off her phone because of her father trying to call her, so no rooster check for her.
The only business this deal (preps party) was good for was Quinn's, at least she hoped it would be.
This said, I agree Sage has a major blind spot concerning Quinn and her motives, Sage isn't stupid and save for some plot twist I can't see any reason she would be that blind.
But hey, as for Jill plot that is a "little" too much, I can live with those downside for the sake of enjoying the whole.
Even with those, BaDIK is still the best game I played on this site.