For example, you could operate (your instance of) your pseudo-legal service yourself, but open-source the codebase (sticking it on GitHub even) and accept patches from anyone.

You could also implement a simple replication architecture for your service, where at any time one node (yours) is considered to be the 'canonical master', and then other nodes can join the network as slaves, receive replicated state, and run as mirrors. Sort of like Linux package repository mirrors.

With such a setup, arresting the original maintainer just means 1. a codebase fork by a new maintainer, and 2. a (probably manual) network master-node election.

And that's just a setup that lets you stay in complete control without having to trust anybody (since you still "own" the codebase, and the master node, until you disappear.) If you are willing to relinquish control to the system itself, you could just build your service on a DHT or a signed store-and-forward hierarchy or a blockchain or whatever. There's no reason that things that are essentially "a BitTorrent tracker exposed through a website" need to have their canonical state anywhere at all.