It's not really a joke. It's more of a "If he really is that upset it is still in print, why doesn't he use at least the sum of money that he originally earned from the book in efforts to take the book off the market somehow?" i.e., litigation, communication with the publishing company, or so on. I think he has to have at least some sort of recourse even though it might be minimal.

And if that is too much of a far reach, it is a "If he is really that upset his book is still in print, instead of profiting off the book, why doesn't he put the money he's made off of it into donations for non-violent support funds or something?"

No matter what he's made money off the book. Until he shows he's really upset about the book still being out there by using that money to do something other than further himself, I'm not convinced he's really that upset about the book being out there. You can't profit from something and simultaenously harp on about how terrible it is.

And if he didn't get royalties, he still profited off the book, and ALSO negotiated himself a terrible publishing deal. Of course, it was like, the 60s, so it's possible he wouldn't know to negotiate a deal any edition of a text about publishing like "Writer's Market" would have been able to outline for him. No internet then. But still, he's made money off it.