Even before Sabrina decides not to send Robertson's soul to Hell, there's already an emissary from Heaven waiting to take him. The fact that this doesn't happen when Sabrina comes for Jimmy Platt is an indication that both sides sending someone to collect every soul is not standard operating procedure. This means that aside from his Deal with the Devil, Robertson lived a virtuous enough life to deserve Heaven, validating Sabrina's decision to spare him eternal damnation.
