Jack foresees attempting to phase though the ice would cause his feet to explode in a gory mess. He also foresees his weapon failing to kill the C.E thanks to his large arsenal of ways to avoid the shot or to block it. He does see one timeline where he manages to kill him but it requires the C.E to want to die.
"Tell me...why? Why murder like this....." C.E asks with a hint of sadness in his voice.