Of course violence of any type is deplorable. You could pick "white" on "white" killings, serial killings, or a whole host of others. But what is the point of protesting those?
Seriously, answer that question in your head. Because, in the end, it's a pointless endeavor. No one in authority is instigating, endorsing, or otherwise perpetuating those evils. And in that critical difference lies the point of his actions.
Again, many of the cited situations are justified on the part of the officer shooting. However, there are several instances where someone loses their life in an unjustified manner, and it we would be morally remiss to treat that as inconsequential.
Is there plenty of crime in this world? Yes, there is. Does it matter when someone loses their life when they don't deserve to? Of course. The distinction he is making is when it happens by the hand of those who swore to serve and protect, then that something needs to be noticed.