I'm not telling you this not because of an emotional connection to cops, I'm telling you this because your word choice harms your credibility.
Of course, some may be swayed one way or the other by the word “pigs.” My guess is that anybody who turns their nose up at the word, or who embraces it for that matter, does so because they have their own built-in biases.
In which case, it may end up being neutral, because the kinds of people dismayed by its use may not have been persuaded by the facts either.
The only people who will discount an argument because of that think Walter Scott had it coming. And they'll believe so right up until it's their family member, and maybe even afterwards.
Also, it's important to correctly convey they are no good cops (1), just pigs. That not one of them can be trusted unless on video from multiple angles. That even the supposedly good ones know and knew what their coworkers were up to and choose to look the other way, even when they don't actively help. That somewhere around our ten thousandth repetition of "just a bad apple" modestly intelligent people have to start considering that it's the whole bushel that's rotten.
(1) yes yes, I'm sure there is at least one in America. Maybe two. The statement stands at 99.99%, ok?