I would just add a rule into the loadbalancer config, if the request is coming from the music industry or a government agency redirect them to an empty website. (I am kidding).
If you want to do one better, put up something like "website blocked" as if it were some overzealous corporate firewall deciding that the site was bad.
With any luck, they'll think it's their own fault.
If you're copying logo or using someone else's trademark from a real firewall page, that's a bad idea. But it can't be too hard to create a generic 'block' page that looks similar enough to real ones without using anyone else's images or logos to be convincing.