She was not an employee. She was not wearing a staples shirt.
OK, good point. I wonder why she went up to that older lady (who had just had a liver transplant, I just learned) so quickly like that, when she was apparently minding her own business? We don't know the entire story. Maybe they had had "words" earlier in the day in the story, off-camera.
However, nothing justifies the way the younger black woman violently flung the older white woman with the mask/shield to the floor like that.