Hate on asteroid detection all you want, call it a waste of time and money if you must, but the partnership drop is actually due to a recent asteroid detection proposal accepted by NASA for consideration called NEOcam.
NASA policy as laid forth in the institution's founding charter, the Space Act, is to avoid competing with private institutions using public money (their baby, JPL).
No, I don't think so. Amy Mainzer's NEOCAM proposal has been in play for several years now, NASA has very broad authority about space act agreements, and the particular SAA with B612 was a no-exchange of funds trade of DSN support for a first cut on asteroid data. If B612 had flown, it might have made the JPL proposal overtaken by events, but that would have made the Discovery program officers happy (by freeing up time and money for the other candidates). I don't thin that the SAA was canceled as JPL protectionism.