Police Action has also come under fire from both sides. Both seem to think the other was given carte blanche by the police, trotting out various videos to the effect. I think the real answer is much simpler. The police were outgunned (or at least at parity) with the supremacists and mid size city cops are not about to get into a gun battle with military grade armaments. This is EXACTLY why the Feds were so obsessed in the 90s. These men are heavily armed, better trained, and take care of their supplies better than the cops. IF they wanted to, they could have taken the town and that is frightening.
Taking down a lone motorist, or a pair, is a much simpler proposition than gunning it out in the open with dozens or hundreds. It was the same thing when police came to round up the murderous bikers after the 2015 Waco shootout, who were going peacefully anyway.

Without saying anything else about police, we can agree that antagonizing scores of armed individuals is something they will neither accept, or be permitted to do.