The difficulty in watching Liber8's actions, is not in their ruthlessness, it's the sheer insanity of causing so many deaths in a time period they weren't expecting to back step to. The collateral damage they choose not to address to the future timeline-one that spawned them, makes their disregard of innocent lives in the present difficult to swallow. At least, you could assume they'd rationalize the deaths they caused back in the future as sacrificing people who participated or benefited from the oppressive corporate regimes. But here, it does come off as mindless, pointless violence in order to make Kiera's quest to capture them all the more heroic. If they showed them adjusting their tactics-as Kellogg tried to convince them, the group and their desire to thwart the coming corp-pocalyse would come off a little better.