I really don't get the point of these messages. You think that the server should've been allowed to run with stolen maps, just because you like it? You really give a bad name for yourself.
i think shutting down server was not justified, let them run their damn server with stolen maps, if your server is competitive enough people will come back. Shutting down rivals server creates really bad precedent, it could be temptative for server owners to shut down competetor servers instead of to compete with them.
unfortunatelly there are little what GK could do to stop using their maps, but enforcing server to shut down is red line.
also there are third party of this battle - players. It looks like you striked both gst and simple players by shutting down server, they have nothing to do with gk maps, but they did hurt.
to generalize all this thoughts - it will hurt community more in long term, then benefit from implementing such methods.