I disagree. This is not even a case of “I feared...etc”
It was outright murder..........................
It will be billed as an accident and an overreaction, and a prosecutor likely won't take the case unless there is enough political pressure and only then if he is the sort to succumb to such pressure.
Cops generally have wide latitude within the legal system. If there is no deliberate intent shown, then everything will be seen in the light which is most helpful to prevent charges against the officer.
If they do go for charges, I expect it to be "negligent homicide."