In the scenario I painted ( poorly I know) , the pilot knows that the destination has deteriorated to the point that it requires an alternate. If the pilot has the option to divert at that point to a suitable airport, but chooses to reduce his/her options to just one airport, an airport that requires an alternate, and then an incident occurs due to the weather deteriorating further, how would you explain the decision? I might be wrong but I doubt you'd be able to convince many that your decision to fly out of range of a suitable airport was a good decision.