For the curious, the request was to share pictures under the hashtag #MyNYPD [1]. The hashtag now mostly consists of meta discussion and news coverage, but there have been a lot of police brutality pictures with that tag.
It could have been a 95% approval rate and I still would have told you this campaign would backfire like this. The minority that dislike the police include many activist groups; if there is anything these activist groups are capable of doing and have the motivation to carry out, it is causing a shitfest on twitter.
Even if you write off those activists as "slacktivists", social media is still their game.
Vitriolic propaganda on social media is far worse than aggressive NYPD officers.