Throwing anything at someone is a violent assault. It is just the degree of violence. Weren't you ever told as a child to "keep your hands to yourself"? Once the veil of no physical contact is breached, where does the escalation stop. Dehumanizing someone is the objective. Once they are not seen an an individual, the individual morals of the mob members won't prevent the mob from escalating the violence up to murder. It works both ways. Once she was assaulted by the crowd, she would have been justified in using her weapon to defend her life.