I think there may be some confusion on this thread.
I dont think there is any excuse for poor airmanship.
OK you can legally be below the localiser in open FIR without communicatiing with the CAS controller but we would all accept this is poor airmanship. From my point of view I should have made this clear. Equally I trust everyone is happy you be there as long as you are communicating. After all it costs nothing.
I suspect there is also an element of education. New pilots may well not appreciate the problems this can cause in bound traffic.
I apologise if I gave an alternative impression. I assume on reflection this was the scenario A and C had in mind.