In my humble opinion, violance and conflict can be lead by anyone. Regardless gender, position, ethnicity, and so on. In this context, violence and conflict can be lead by a male leaders or female leaders depand on their characteristics.
I understand the statement why male leaders always lead us to violance and conflict. Although in here we does not provided by the data how much violance and conflict lead by male leaders versus violance and conflict lead by female leaders, we can say that maybe because male leaders mostly use their logics rather (typical of male) than female leaders. But it does not guarantee that male leaders always lead us to violance and conflct.
We know Margareth Thatcher, former Prime Minister of United Kingdom, who lead United Kingdom in catastrophic violance and conflict called World War II. She also decide whether United Kingdom joined World War II or not.
On the other side of world we have Soekarno, the first President of Indonesia, who lead people of Inonesia on violance and conflict with Netherland (country which inhibated Indonesia for 350 years). Unter his leadership, Indonesia can gain freedom on 17 August 1945.
From two story that I have described before, we can say that whoever the leaders can lead ud to violance and conflict. It also applied to peaceful. Whoever the leaders, regardless their gender, etchnicity, and so on can also peaceful. Violance, conflict, peace not depend on gender. Both male or female can lead to violance and conflict or lead to peace.