Important question; author kind of answers here:
https://lemmy.dbzer0.com/comment/204729
If I were to rely on this for my instance, I would require that it be completely transparent and open source. It doesn’t look like this is; you have to trust that it is making good selections, and give it power over your federation status. It’s a dangerous tool, IMO, but I can understand why it would have appeal right now.
“The Lemmy Overseer” as I understand it is a backend service that gives us an API to use.
There is an open-source script for interacting with it. However, it does not tell you how that backend service works, exactly. It’s a black box with well defined interfaces, best case, as I understand it.