That image isn't saying that they aren't hard right. It's saying the standard spectrum of left right doesn't account for how practically similar the two extremes actually are in how they operate.
Bear in mind that we are actually talking about extremes at those ends of the shoe. Genocidal dictators. Trump is not Hitler or Stalin. He's not that far around the horseshoe, yet.
Police killings are already statistically very rare. Much more so than other types, which are already pretty rare.
Not to mention that the definition here of red vs blue is being held static, despite it actually changing (potentially) every 4 years.