Police, like everyone else, are not perfect automatons... there is always the possibility of any, physically possible, behaviour occurring in any place and in any time.

Of course it is always possible to modulate people’s behaviour through incentives and so on, to achieve a very high probability that they will behave in certain ways.

In this case it seems that the balance was in favor of the protestors.

Yes, how convenient this time, in comparison to the BLM protests which were met with militarized police against peaceful protestors.

I think the definition they used of "peaceful" (given context) was different.