The author didn't owe anyone a filesystem encryption program. He still gave one to people for his own reasons. The fact that some people are pissed about the thing he gave them for free says more about those people than it does about him.
He doesn't owe anyone anything.
EDIT Fox must have good lawyers because I couldn't find Comic Book Guy complaining about how Itchy & Scratchy owe him because they've given him hundreds of hours of entertainment for free.
Jeez... nobody says he owes anything to anyone. Nobody said that people are pissed (maybe you are?) I think people are just disappointed because he destroyed something really valuable and he clearly hampers any attempts to recover that damage.
He doesn't owe anyone anything.
EDIT Fox must have good lawyers because I couldn't find Comic Book Guy complaining about how Itchy & Scratchy owe him because they've given him hundreds of hours of entertainment for free.