Actually met this guy and another last week for a road ride.
The person in question is 75 years old, and has can't see out of his right eye. So he wants to ride mostly bike path, but he also rides a stretch on the sidewalk.
So I say to him, cyclists over 12 shouldn't ride on the sidewalk. He says he can see the cars pulling out of driveways but can't see the cars coming behind him. I say, you are blind in the right eye, so unless you have your head on a swivel, you can't see cars coming out of driveways. Meanwhile the other guy tells me to be quiet, that if he made it to 75 riding on sidewalks, he must know a thing or two. I think he was just lucky, and it is only a matter of time.
Sorry for the rant, but it shocks me when people who have been biking for decades still get safety wrong.