I think instance admins can transfer moderator powers by request, if absentee moderation should become an issue.

We can indeed. If a user if the instance, who is in good standing, would like to take up the reins moderating a community they often post to, then they can drop us a note a and we'll look into it. We do keep an eye out for enthusatic posters to communities without an active Mod and might reach out to them but there's no harm in being proactive.