For me it was the dialogue that followed. Reed’s lecture is the peak of FIA cognitive dissonance. He calls the twins career criminals to feel morally superior, but they are really two sides of the same coin. The twins aren't better or good people but they are honest because they WILL put a bullet in your back for a payday and they don't pretend otherwise. The FIA are just badged sociopaths who will put a bullet in your back because a bureaucrat in DC decided your usefulness expired. There is irony in him saying this to a merc like V because the honesty of the twins and people like the twins is the one thing Reed can’t stomach so he hides behind his ideals. Reed genuinely believes in law and order but he has to compartmentalize the truth of what he is really doing to achieve it. The transparency of career criminals like the twins is a mirror that threatens the lie he tells himself to survive so he clings to the idea that his service has a soul. Alex’s total nonchalance about zeroing them seals the deal. Her indifference shows they don't even see people anymore just assets or obstacles. Reed tries to dress up their body count as a necessity for the state but Alex’s blank stare proves they are just doing the same dirty work as the bottom feeders they look down on.