What I'm saying is that 5.45x39mm is hard to find right now. Whether it's a de facto ban or not (on the rifles that shoot 5.45x39mm ammunition) depends on what the cause is for the shortage. If there is ammo 'waiting at the port' and some petty tyrant is stopping its distribution, then it is a ban. If the ammo is being used elsewhere in the world (or any other reason), then I would see this as a great demonstration of why it is unwise not to have some extra ammunition available for your guns.
I am not sure that many people would care about the unavailability of a caliber that they don't own. Joe Hunter most definately would not - the 5.45mm packs about the same juice as a .223rem, which is considerably easier to come by.