I think he knows it's wrong, but the beast is unleashed. That's what he is.
Or could it be that the writers have long ago forgotten how to write Jack as a consistent character? Thus, he is murder man in one second and remorseful tired old vet the next second.
EDIT:
You're basically asking them not to acknowledge his character development.
What character development? That bad shit has happened to him? Bad shit happens to Jack Bauer every day.