Pay Evil Unto Evil: How played straight it is depends upon your taste, really. Imperial justice and generic morality will happily kill Evil (or Orange, if you prefer) of adequate magnitude and walk off feeling good about it, and finds mercy, on the whole and vis-à-vis clemency, to be one of those quaint incomprehensible (well, okay, the concept is comprehensible, but why we think it’s useful, or rather that we continue to think that it’s useful when there’s no actual specifiable utility in it, again vis-à-vis clemency, isn’t) foreign concepts… but on the other hand, is quite insistent on just killing evil. You’re saving the universe for decency and civilization. No need to be all gratuitous about it, especially if that would be all tasteless and unnecessarily entropic.
(Note: humorously ironic probably doesn’t count as gratuitous for these purposes.)