Per the standing rules, you can claim pretty much any land and start creating on it. If it has sat for a month, it is free game.
I don't think a purge or maintenance is needed, just stake a secondary claim the territory you want to work and do your thing. If the person comes back, will be collaboration. Shouldn't be a problem, has happened to a few of them already. Creative is creative is creative. Even if it doesn't match what the original author was thinking...who cares. Alternate history? Call it a fork of the current land? Still good creative stuff going on and that is the point.
That being said, I am working on Vartanadel which should give me 3 more months to add the expansions I am working on. Wouldn't care if people did stuff to it. I am doing my thing and may or may not use something they added. The beauty of the entire thing.
So, go for it Fiendrunner!!!