For some reason, Saw said, "You've been indirectly killing people all this time, so seeing people die yourself makes you feel guilty?" I think he'll say
"Hello Red. I'm sure you're wondering what is going on. Before you either killed people as an imposter or denied any responsibilty for your collegues' murders as a crewmate. And it was just a game for you. Now you will play mine. From which there won't be an escape... unless through the same road that your victims went through in your presence. Live or die; Red, the choice is yours."