There seems to be some confusion about the rules Ian, from many angles.
Just because you're registered disabled doesn't make you elligible to shoot the alternative positions. What makes you elligible is if you are (to quote exactly the rules) unable
, for a medical reason. I think the fact that you have said you can
shoot from the position means you are thus not unable (here's where you said you could
). That in my book, and perhaps others makes you illegible. Because if the medical reason made you unable then you wouldn't have been able to post the groups. It may be uncomfortable, it may even do damage, but then if i show the standard 10m position to a back expert, complain of a bad back, i don't expect he'd have much issue in saying there's a medical reason why i shouldn't. There might be more of a problem if he was to specifically say I was unable. You have shown you are able.
But have you conveyed that each time to the CM when you asked for permission to shoot your alternative?
Perhaps the rules just need explaining to both yourself and the CM to avoid all this for the next shoot.