It's about something which happened to limit this person's mobility and how it give them more empathy for people with impaired mobility and other disabilities. The point is that accessibility is important for each and every one of us.
The audience for a given Hacker News article is the people who show up and find it interesting, rather than some platonic ideal of a Hacker News user. Participating in a system based on voting (such as HN) means accepting you won't always get your way. There are stories on the front page that aren't inappropriate/flaggable but which I would rather weren't there every day.