I would expect that Gabe is trying to hedge his bets and make the company more of a co-op, where several key figures in the company as well as himself, own the majority, so that there's accountability in what everyone decides.

That way if someone's kid ends up inheriting stock in valve, there's a way to block them out of major decisions if there's a need to.

If that's indeed what's happening, then it's a very long-term play by Gabe. He's looking so fast ahead, so that long after he's departed the company, the values that make valve great (and successful) will endure.