I remember many years ago when in India and my meditation teacher, Swami Veda Bharati hired armed guards to protect the ashram from thugs who were trying to take it over. At the time, I wondered how my gentle teacher, who was a master of ahimsa, could do this.
Ahimsa, non-violence, is the first and most basic practice of yoga, and it is natural that beginning practitioners of yoga sometimes mistakenly believe that they must repress and suppress any forcefulness in their personality and always be "nice". But yoga does not require its practitioners to become doormats. The practice of ahimsa, like all yoga practices, requires discrimination to practice correctly.
Look at another master of ahimsa, M. K.(Mahatma) Gandi, whose very active non-violent protests overcame the might of the British Empire. Certainly, Gandhi was not a doormat.
It has taken me many years to understand and to begin to apply this principle in my own life. The key, as later explained to me by Swami Veda, is to use the least force necessary to protect yourself and others from harm. So, one may be very assertive while practicing ahimsa.
If someone is trying to harm you, it is your right and even your duty to defend yourself and respond in a way that is appropriate to the circumstance. So that even a true practitioner of ahimsa might find himself employing guards with guns in the right situation.