So you don’t supervise your cat while he’s out, is what I’m getting. Ok.
Then I sincerely hope your elderly cat, who REACHED his age by being kept indoors, doesn’t end up hit by a car, accidentally eating poison or something poisonous, or depending on where you live, eaten by a coyote or gator. As happens to many cats allowed outdoors unsupervised.
If you let a cat out, be responsible by supervising and leashing/harnessing it or have a special enclosed cat run in your yard.