To many, Richard Simmons is a beloved celebrity. It makes perfect sense for people who are fans of his, or who have followed along with his workout videos and gotten in better shape, to be worried about him, especially when he was out of the spotlight for as long as he had been.
Richard Simmons is a grown man who has proven to be capable of caring for himself. Since he is a fitness fanatic and his health-conscious, I do not believe there are any underlying reasons as to why his lack of being seen in public is a problem. I believe that Richard Simmons is enjoying his privacy and that is why he hasn't been heard from too much lately.
Celebrities come and go. They appear in the spotlight frequently one week, and the next week they are completely absent from the papers. They do this by avoiding places with paparazzi and staying home. Richard Simmons could be simply removing himself from the public for a number of reasons, which are none of the public concerns.
No, I do not think the public should be worried about Richard Simmons because Simmons probably has a good support system around him to help him see this situation through. Simmons has always been an eccentric guy, and I believe that he will find help and come out better in the future.