For the average human going about an ordinary and active life that statement is quite true.
However, the person in question didn't lead an ordinary life. He was confined to a medical device and probably very rarely had in-person contact with random people. Besides, the people who met him personally all must have known about his condition.
Under such circumstances avoiding COVID-19 is actually pretty easy: Have everyone in the room wear high-quality face masks.
Even for the average person during the height of the pandemic, avoiding COVID-19 was still possible, but required significant effort (no lockdowns though, mind you): Basically, it meant wearing such a mask properly in public settings (and changing it at appropriate intervals) as well as frequent testing of everyone you were in touch with regularly.