Even if that were true (Jason had killed lots of people already, it's not like his hands weren't soaked with blood), it reminds me of that time Joker poisoned Lois and tricked Supes into thinking that only killing him could save her, and Supes went all "oh, Lois, I was going to let you die because I knew you'd rather be dead than know that I killed the Joker for your sake!"
In both cases, my reply is something along the lines of "O RLY?"