Buddhists on the whole are peaceful and seek non-violent solutions to conflict. Individual Buddhists depending upon the school and tradition may be completely pacifistic like Tibetan Buddhist Lamas or they may allow for violence only in self defense such as Chinese Shaolin Monks.
Honestly this looks like a cult that takes a little from Buddhist teachings but is no more Buddhist than the Unification Church is Christian. The 969 Squad has a charismatic leader who adds his own political agenda of racism and bigotry to traditional Buddhist teachings. He literalizes sutras to justify his call to violence. Ashin Wirathu is a monk. He may not have achieved any type of mindfulness or equanimity as he preaches hatred towards Muslims and fierce attachment to patriotism. The first act of the Buddha was to renounce his own family, heritage, and birthright and go forth in search of the end of suffering and the realization of well being. This man has never left home.
Bluntly he is a sociopathic asshole who is no different than Hitler, Sun Myung Moon, or David Koresh. He uses the trappings of the dominant religion of his country to mask his hatred, bigotry, racism, and seething rage. he revels in the cult worship of his 'followers'. He deserves only pity and nothing more.