Policeman slashed by amok man

According to a MI report (here), a policeman was slashed by a man who ran amok. In such a situation where the policeman's life was being threatened, why hasn't he used his gun? It would have been justified as according to Inspector-General’s Standing Orders (IGSO), a policeman can take out his gun and use it when the "policemen believe that their lives are in imminent danger of serious injuries or death when apprehending or confronting a suspect;" and "other people’s lives are in imminent danger of serious injuries or death." The use of a firearm would have been justified here as the elements of a life threatening situation and imminent danger to other people are clearly displayed. There wont be any police bashing here. Instead the 2 poicemen should be recommended for being level headed by first trying to pacify the man who had already started running amok. However they should have first assessed the situation before approaching the man.