Signal boosting games that could already be published as Early Access on Steam is absolutely the way to go. It's still a fraught path, of course, because many early access games are darlings at first, and then the developer loses their commitment, and things go off the rails.
But you're right. If he's smart, he'll be concentrating almost exclusively on those 80-100% complete projects, and probably make some money doing so.
It's way too early days for him to be contemplating stepping into the early stages of a game. Realistically, a few hours after announcement, inbox is probably already flooded with proof positive of what a Sisyphean chore that would be.