Here's a thought, maybe part of the reason Nick panicked was because, as others have theorized, he let Vinny in that night. Vinny had nothing to do with the Cathy picture, but Nick did not know that and assumed Vinny did. That seems to fit the kind of bait and switch DPC favors, does it not?
That would leave us back to Ron or Sally or someone in Magnar's orbit having actually taken the pic of Cathy and posted it by remote log in using a captured password via a keylogger buried in the Brawler app.
Does that fit?