Hehe, they did already. At least here in France anywhere in public.But they can not ban burkas, can they?
Well, if you had your chin firmly against the chest, then it is not surprising you did not see you packing in the mirror, you probably just saw your feetI went to the bathroom in front of the mirror just to check: It took more time to pack my lungs but there was nothing moving while I was packing thru nose but the chin has to be firmly against the chest...
But seriously, I really wonder how you make the buccal pump without moving the jaw. Are you sure you are really packing (doing glossopharyngeal insuflation)? Or are just simply adding some air by couple of small extra inhales? Maybe you could post a video
However, regardless whether you can hide the packing or not, if someone wants to ban it, he can simply tell the divers that they have to dive within something like 5s after taking the final big inhale (or even less). Problem solved.