If he doesn't want to ruin his personal experience of it too much, he could license the name and UI in some way to a developer whereby the developer gets some return, but the bulk goes to a foundation of his choosing. That way he doesn't get too embroiled in the work aspect. The clones are inevitable, so might as well head them off and continue the positive vibe.

(My wife and I play it, as does our 9yo. It's a morning (LOL, 00:01...) ritual of sorts, playing and then later discussing our tactics and the logic involved.