Well Ruud who runs .world also runs Mastodon.world which is a fairly large mastodon instance, so he is somewhat of a known quantity and has experience running large Fediverse servers. His mastodon server has handled a large population and donations happen through Open Collective for transparency as well. He also runs Calckey.world though that is much smaller.
The danger in randomizing servers is that some smaller servers not only have less than 99% uptime but are also just run by random regular people who couldn’t handle the increased load and/or have no desire or ability to keep the servers running long term. It could maybe work if the randomization occurs from within a vetted list.
Account migration is a feature that has been noted for the future and would indeed be very important since it would essentially make the entire network bulletproof. Being able to move instances and/or link accounts across multiple instances would create the necessary redundancy and reduce fears of choosing a smaller instance as home.
Not really. Also by your logic you can’t trust anyone ever because there is always a risk they turn bad at some point in the future. All we can do is evaluate what we have in front of us at the moment. Current evidence suggests Ruud is trustworthy, committed and capable of running a large Fediverse instance.