The issue isn’t even just “him vs corporation with expensive lawyers”. There’s also no legal basis for any kind of action.

I’ve said in another post that I’m all for legislation that changes the obligations software developers have when selling software, such that abandoning hosting for software that requires access to their server comes with the obligation that they enable third parties to replace the functionality and consumers don’t lose access. But there aren’t any laws that can be interpreted that way. At absolute most, some very recent purchasers might be entitled to a refund. And if you could write such a law in a coherent way, and find a way to get it passed, it would still almost certainly only be able to apply to future software sales, not be retroactive.