Not only a mature man can get an erection from such a sight, but even an old man can get an erection from such a sight. He was very lucky that he caught the masturbating babysitter, because the girl is very appetizing and her pussy and ass just alluring with its narrow hole, into which I would also dive with pleasure.
Man is old and fat, it's hard for him to cope with such a temperamental beastie! I think she always has a couple of young guys to help her out. So grandpa probably has antlers like a reindeer!