I had not heard of Kayak Bill until reading the article in December. I don’t think we need to admire him or ignore the story. As you say he made no demands on Society.
If he was suffering in his former life, then he did what most people do in this world. Change it.
He walked away Is this selfish? I don’t think so.
I Kayak and I camp (wilderness preferred) I leave my wife and kids most weekends to go Kayak camping. Its called walkabout….. food for the soul. My wife of (33 years) understands this urge so do my children.
What has he given to Society? Probably nothing more than an insight for us to see into a small part of the life of a person who has challenged life, nature and all it had to throw at him.