Well, Anglika. I did love his phraseology as well, i.e. until I started my translation.

That which works so well in English, is not as straightforward when translated.
Uncalled for treachery fits the context very well. About the second one, I see your point, and agree. However, who has a passion of unrighteousness for its own sake, i.e. a passion for crime for its own sake? But then again, its being stated that not even something as base as that could excuse an uncalled for treachery, so ...