Web of trust.

You could auto-mute anyone who is completely outside your web of trust without any one step connection to accounts you know. And the ability to see it in the list so you can expand, versus completely hiding it could also be based on degrees of separation. ie. More than 6 degrees? Hide completely. 5 degrees or less, leave a “show post” option for muted comments.

Leveraging the web of trust is a massively underappreciated tool, imo.