Tourist,
I'm very surprised someone as apparently well informed as you didn't know WSOs were still being commissioned and I'm sure that you know all rear crew training is now the responsibility of 45(R) Sqn. With, in the future, big help from 750 NAS for WSOp sensor.
But that's not the point your trying to make is it, your point is the RAF has no way of training WSOs from civvy Street. My point is it doesn't have to.