-There is no community to form to initiate an RfA of some type for another admin
This is the bit I don't get. You mention the admin being abusive to members of the community, yet say there is no community. The amount of community required to make a new admin on a small project is tiny. One person willing to do it, one person supporting them and no-one (other than the rogue admin) objecting is all that should be required to get a steward to promote. It seems like there is enough of a community for that.
There are longer term questions that will have to be dealt with by someone other than us: -How does one reconstitute a community that's had a crisis of confidence? -How do we locate someone in a fractured community to give the sysop bit to when reasonable people may have been run-off from the project?
The other Russian projects might be able to help. Put a notice somewhere on ruwiki, say, telling people that this project needs fresh blood, and hopefully a handful of people will take up the challenge. It only needs 3 or 4 people, really.
-How do we keep it from happening again?
Strongly discourage projects having only one admin. I wouldn't ban it completely, as someone suggested earlier, since that would stop one person being able to found a new project, but once a community reaches a reasonable size to have multiple admins, it should do so. Perhaps we should have a central policy on choosing admins for small projects. Something like: On any project with fewer than 3 active admins (defined as having used admin tools in the last month), anyone wishing to become an admin can do so by creating a page linked to from the village pump (or equivalent) and if, after a week of voting, there is a simply majority in favour (anyone with more than 50 edits on the project can vote, sockpuppets are discounted), they can go to the stewards and get promoted.
At the moment, each project has it's own system for appointing admins, which makes it very difficult for small projects to get new admins, since they first have to develop a consensus on how to do it. Imposing a central method on small projects would remove that hurdle.