I did read the article and I actually watched the film.
Maybe you should do that, rather than taking what you are told at face value.
She is being held by 2 cops, her body is pressed up against the vehicle, and she is still holding a 3 year old in he arms when this cop punched her twice (at least in the face).
video on the article page, right at the 1:24 mark.
If you think this cops actions are justified, then there is no hope for you.
So, then, you have no answer?
Surprise, surprise! /s
No officer anywhere is trained for such a scenario.
A hostile mother resisting arrest, proclaiming the officers would have to shoot her leaves few options.
Waiting for how you think that they should have reacted to protect the only innocent in this scenario (the baby).