[MN BB Ref]

I agree with both PA Coach and stewcall here as they are both correct. The R does have responsibility for ensuring that the shot was before the expiration of time. The L has the responsibility for determining if the shot was by Team A.

In this case the shot was before the buzzer but not a legal shot. It is L's responsibility to stay on the court and have the officiating crew retrieved. He/she then has to tell the R what he/she saw transpire and ultimately it is the R's decision to make as that is the responsibility of the R. He/she is the final authority on all matters of rule interpretation and disputes on the court. He/she can elect to change the call or keep it. In either case L will be able to sleep at night because he/she did the right thing.