Planting porn or other questionable content on an opponent's device is an old hacker tactic. It has actually been used successfully as reasonable doubt in some cases when someone was found to have it on their computer (and I've known a few people who got malware that planted it on their computer before). The big question is where it comes from, by what direction, and for what reason. Most of the time, it is just a shotgun attack, send out millions and millions of spam emails and hope someone clicks on something.