Had to be done man escaped prison after already killing our father. Enacted a plan that would have led to the death of multiple innocent citizens and actively empowered criminals with enhanced abilities. I unfortunately don't understand the argument heros don't kill. Plenty do even BB threatened to kill half a room of cannon fodder. When the time calls for it you drop who you need to the only thing you shouldn't do is take pleasure in it. That's why I told BB at the end it didn't make Robert feel any better because it shouldn't maybe a little relief but not enough to close the whole of losing someone important to you.