Timothy to be fair it was you who introduced the dumping concept.
This implies returning from france at fl65 to be told by london to continue with london info because you are too low for an airways clearance. Descending ocas for a class g arrival is a diiferent matter. You have not exactly be dumped but have elected to leave the system for reasons of necessity.
Never the less i dont follow your concern about the pilot flying the ma. As matters stand if the pilot is not visual by the faf he is going elsewhere. At that point he is some way away from the final approach track so the ma is hardly appropriate. As he is ocas he would presumably inform at that he was not visual at the faf and would continue on heading x with a request to climb to y and depart own navigation on a heading of z for his diversion.
In my opinion i come back to the point i made earlier it is just daft that a pilot would be persuaded to leave cas on the strength of a metar for a descent to a point that might be miles away from the airfield. If on the other hand he knew the metar coincided with weather at the point at which he was descending he would make a sensible judgement call as to whether or not he expected to be visual by that point and if he didnt before leaving the comfort of cas would go elsewhere.
Unless you know differently it seems to me most airports with an iap in class g have almost no traffic when the weather is poor and i doubt if it is that poor the eir holder will have much chance of being visual by the faf. Never the less if he elects to prove the metar wrong i doubt he will cause at too many problems.