first thing...fantastic site. with respect to this problem, what prevents white from simply moving his king out of check, rather than interposing his bishop?
1.Qc6 Qd4+ 2.Be3 QxB+ 3.Rcf2 only loses the bishop.
otherwise after 2. Kh1 Rac8 3.Qf3 RxR, loses the a rook.
So, white is basically sacrificing the bishop to save his rook.
