The role, skill sets, entry requirements and depth/length of training for NCA and RAF Cabin Crew are entirely different. It’s completely inappropriate to compare rank between the two trades.
RAF Cabin Crew do not attend OASC nor do they complete MAGS. In addition, Voyager cabin crew training is only 3 weeks, does this make them “aircrew”? Especially given that it’s still a ground trade with an airborne role however, this is slowly changing as the ground role is phased out. That said, the vast majority are professionals and are good in the role, I don't think people will be serious in calling them aircrew until its a pure aviation role without the ground element.
The wearing of their CC “trade” badge is iaw dress regs and worn on their arm, I personally don’t have a problem with it being worn on their left shoulder in the form of a name badge on a flying suit.
The captain has ultimate authority over all pax and the Senior Cabin Crew Member is a SNCO, having all further 7 cabin crew hold SNCO tank is inappropriate, unnecessary and overkill. Squaddies get on a Voyager (as they have done for 7 years or so) eat, sleep and get off. Passengers are well aware of the fact they are to follow all commands given by the crew, if they don’t the SCCM will step in, I’m not sure why some people think that passengers require three strips and a big stick to keep them in line.