While all of that is true, there are some (clearly not enough) who understand that The Punisher as a character and concept addresses the failures of law enforcement.
Maybe the guy was simply a fan and that's all it was. Idk. But considering everything else going on in that video, the wallpaper or screensaver on a cop's phone seems like a trivial thing to complain about. I didn't think twice about it when I first saw it. What bothers me a whole lot more is these idiot cops not doing anything while kids were getting murdered while they waited.