This was my first reaction to him posting this. We know Leon hates a large portion of people, calling most parasites and such. He also does not think he is ever wrong and wouldn’t feel the need to defend himself by shifting blame, he would want the praise of ridding the world of people. He also fancies himself “clever” by saying things that mean something else and can then defect criticism with his great intellect and silly arguments. So this seems to be him telling people it would be ok to kill on his behalf and they need to be ready to do it. Of course he probably loves the idea of defending Nazis for funsies too.