1) Post the email, I want to see if I can arrange a diplomatic email: This is also historic and news worthy
2) For now, post in Russian that you are "getting a lawyer" and CC Russian lawyers on twitter.
3) If you haven't read the >>>/n/156 : Russia has actually banned VPNs & TOR: legally you cannot recommend the address. You can do a canary like post although: "This image is soo cool! [contains the addresses]
4) For now reply with "While we are getting a lawyer, we are seeking advice on what our best options are for our international users whose these bodies of works are legal to, and belong to those owners on those countries."

This might get international headlines if you seekout the correct people.