Developer usurpation is a pheomonen in real estate in which a developer puts pressure on local government to use its power of eminent domain to reapportion land ownership without just consideration of the public good.
In a wiki, the equivalent is when a usurper with technical skills or technological access that the ordinary sysop doesn't have, over-rides the sysop power structure to put block IP measures or other restrictions in place that make it impossible for the sysop to undo what the developer does. This reapportions user attention to suit the developer, over-riding the due process.
This is a power play of the most extreme kind, and strongly frowned upon even when it is done under the direct order of a GodKing. It makes it obvious that there is a power structure that is quite different from that which is "negotiated" in the "virtual community" - and in fact proves that there is no such community or community-managed space, but merely something like a corporate shopping mall, where presence is at the sufference of security guards.