From another comment, it was released by their internal startup incubator. It's potentially not related to anything else at all inside Google, just a project a small team was able to put together with Google's money.
Thank you for the information. I did not see it.
While I suspect there's no deep strategy behind it, one could argue that there's the possibility that long-term, future social networks are going to pop up inside things like Fortnite or Minecraft, and Google would want to capture as much of that space as possible (and sell adverts into it).
Google is always focused on AI. I am pretty sure there will be AI among the players who will behave like humans. Maybe your best friend in game will be an AI.
I find this comment fascinating. I wonder how you came to think this was a tool for AI... I can't see it because it very clearly just looks like Minecraft with some basic scripting. No one is going to be building advanced ai in something like that.