> It doesn't appear, though, that the author was part of that team
Apparently, there was some sort of agreement that OP would not be disclosing his own related work independently of Kenneth. This makes him very much "part of the team" in a rather significant sense, and he does seem to share some responsibility from that POV.
It doesn't appear, though, that the author was part of that team, or promised any of the money.
The author says this:
"If he'd found another way to use the money on Requests, then I would have been totally happy. I didn't have any claim on the money"
Other parts of the post do seem to indicate something isn't right. But it's not exactly as straightforward as you're saying.