For you, there is positive utility in that which is objective

For them, the objective carries negative utility - so they don't engage with it

So if you want to change their position, you can not do so with truth, and must do so entirely on narrative. Make them believe that supporting the police when they do nothing wrong against a criminal who made his life, and they'll suddenly find all the evidence in the world supporting that position. But you have to sell them on the position first, not the evidence.