Meh. He's not harming anyone is he? The Royal connection gives it some credibility unlike a certain R Sigs Major (retd) I know in Civvy Street who, to this day, practices foot drill in front of bemused co-workers.
It's not honorary, the rank and commission is still held. By practice, as I understand it, it starts at Major but there is some horsey thing going on with Capt Phillips and I was a mere digger of trenches and carrier of SLR/SA80 and am not worthy.