I don't know how many senior nudists there are, but whatever their numbers are you can count me in. It's a wonderful life's experience and shouldn't be discouraged because of age. Beauty is in the eye of the beholder and I quite like to see a fit and healthy nudist at 50+.
73 here -- in the summer months I have gone weeks without wearing anything. Cooler here now, so have to wear something, but take it off as soon as I get home. My body is getting older but am still young inside. Love working in the yard, neighbors on all sides are either naturalists or gay, so there is no problem with being naked in the backyard. I haven't gone completely naked in the front yard - yet. It's a little too public out there. Usually wear a wrap and sandles when working in the front yard.