When the threat to your survival is sufficiently large (as it is when there are only 50,000 humans left), yes. Pondering the morality of war is a luxury that people not facing extinction have. It's one of the reasons why the behavior of the characters in the show often rings hallow. They frequently act like the don't really care if humans make it or not and that's a pretty standard leftist world-view, that it doesn't matter which side wins.
As Patton observed (in 1930), "War is not a contest with gloves. It is resorted to only when laws (which are rules) have failed:" I highly recommend this essay.
Funny the guy named question_assumptions is saying genocide should be attempted without bothering to spend a couple minutes to say “are we sure”.