So my question today is:
How will mastodon be governed? What's to stop the bad guys opening up instances and joining the federation?
Who says that subversive content is not allowed and should be taken off the instance, or banned.
Lots of challenges for a nascent platform I think..

@eileenb Admins and instances are autonomous. Each can decide what instances they do (or don't) peer with. This isn't unlike other network protocols like email (SMTP) or internet routing (BGP). There are channels for admins to talk to each other (an organisational mailing list), and tools which are built into protocols and servers themselves (Mastodon is only one of several at play).

It's safe to assume bad guys /will/ open instances, or worse, guys or girls who simply don't care what happens.

@eileenb The reason the "we don't care" attitude sucks is that shunning such an instance will hurt a bunch of innocents -- they become human shields, effectively. My recommendation to the fediverse would be "suck it up and take the hit". Though migration tools would be really, really, really nice to have in that case.