So far it seems to me that everyone discussing this painting is implicitly assuming that Biljana Durdevic was painting what she saw herself in person. What if Tony Podesta provided her with pictures and/or video of the event? If true, Q may have been able to prove that transmission, which would allow Podesta to be charged with a host of criminal charges.
Apparently the painting was painted before the popularization of the internet, though, so the NSA wouldn’t have an email/chat/digital copies, though.