Mark imported instances with <import-mastodont>

[samuk]

Where instances have been added to a blocklist using this tool add reason 'import-mastodont' to the blocking reason published by the server.

Then when running your script to generate the most-defederated list you could exclude those added by this tool.

Otherwise if it gets reasonable adoption you have some circularity, it's on the list because it's on the list, and lots of instances subscribe to the list.

Being on a blocklist is not a good reason for being on a blocklist..