You're completely missing Blackwing's point. Blackwing argued that lying in a pit in a dungeon, stricken with depression, would not undo the serious harm that V's actions caused. Besides the mass murder V engaged in, V murdered the Draketooths, allowing actual villains like the Linear Guild, Team Tarquin, and of course Team Evil, free reign to saunter into the pyramid at their leisure. Blackwing was reminding V that she had a duty to set right at least part of the harm she'd caused, regardless of whether that would atone for the mass murder or not. Vaarsuvius recognized the sense in Blackwing's words and was ready to rejoin the Order, before a Mummy fell on her.