People like to think Asimov predicted the current technology known as "artificial intelligence". They are wrong. It was Douglas Adams when a computer spent untold resources just to return an answer which is both irrelevant and poses further questions.
Mastodon should ask you to pick a "moderator" not an "instance".
The latter is obscure technical detail. The former is about people, and power, and explainable to anyone.
"You pick which person or organisation you want to decide who and what is banned. You can change it later."