The thing to keep in mind is that song is clearly song sung by someone who doesnt like Ozpin and this its biased.
And its not the first time we have seen songs that are clearly biased and not telling the truth Salem's song comes to mind.
So we should take songs as not fact when they are like this because A we have been told by Jeff that songs are not exactly about the Lyrics but rather the emotion they express.
B because people who are enemies are naturally going to take you at your worst and apply traits you dont have because they are warping your intent and behavior's under that viewpoint of being opposite sides.
Also keep in mind Ozpin in regards to the ancient things may not have a choice. We know Salem is after the Maidens because they are the keys to the vault which in turn house the relics which are ancient as all get out.
So his enemy is focused on and working towards the ancient ways ie the Relics which are dangerous so Ozpin MUST respond in kind even though he does have them and instead of using them he locked them away.