YJ: YA is the only creditor with a secured claim. Managers will hold unsecured priority claim which will still be worthless. In your proposed BK, shareholders fall in third as unsecured nonpriority claims.
YA already owns 100% of assets through the credit agreements - so holding "say 95%" of shares is a weaker position because common shareholers hold 3rd place unsecured nonpriority status. They want to be holding 0 shares in a BK because "there will be NOTHING left over for shareholders."
So there is no reason for YA to go through the expense and exposure risk of a R/S in order to do a BK. They don't need it.