There are always things like real people and phone numbers. You know, find some GH staffers via G+, LinkedIn, Fb or your own network of friends and work some connections. Pete does not say the lengths he went to, but email is admittedly one of the most passive mediums.
You really should not have to find people working at GitHub on other parts of the internet for something like dealing with copyright issues if you're not the copyright owner because (I suspect) copyright owners will have no trouble getting GitHub to (at least) listen to their complaints.
