Oh, ye of little faith!
I'm led to believe, from a well placed source, that things are being addressed. Messages on the screens have been changed to say that 'Off Peak tickets MAY not be valid on this service' and further information is given regarding journeys that have started outside London. With a request to ask staff if unsure.
Staff have also been briefed as well.
If this is indeed the case then it is good to see swift action taken to address the issue of Off Peak restrictions, or the lack of them, through Paddington in the evening peak.
I'll be looking out for any updated information the next time I travel through Paddington.