This is a little late in the day , however your CB cannot give you a NC just because you have not tested your supplier's BCP.
They can however give you an NC if you were unable to show with reasonable confidence that your supplier has reasonable Business Continuity measures in place.
Here again note that , to what extent you need to show that confidence depends completely upon
a) Nature of your supplier ( You cant make depends to supplier like Microsoft or your local power company )
b) what is the dependence criticality your business have on your supplier . for example you don't go asking for BCP & BCMS compliance to your local vendor who supplies you office stationary until and unless your business suffers drastically due to their non delivery .