The logically and ethically correct response, as usual, is the one drawn from leftist theory.
Killing in self defense has been a cornerstone of human legal systems since human society has existed.
Violence comes in many forms. This time it was a bullet. It could be a denied healthcare claim. It could be excessive copays and deductibles. It could be wage theft. It could be abuse of workplace power dynamics.
Employers shouldn’t have started the violence if they didn’t want people to start defending themselves.
That’s the funny thing about an ideology being objectively logically and ethically correct. The framework of theory also consistently addresses those exact points and material conditions.