If any company has an employee threaten violence and does not remove that person and then that person does harm someone they can expect to be sued at least and maybe wind up as a codefendant in this liberal world we now live in.
Even if she doesn’t actually stab anyone, she has demonstrated that she is extremely emotional to the point of appearing mentally disturbed, lacks judgement (by putting the video out on social media) and generally is NOT the kind of person you want involved with anything important.