Would you mind it if jon does not follow his father's code of morality including the no kill rule? He wears the symbol of the EL household. But, does he have to live by their standard. What portrayal do you like or want, jon-the rebel or jon-the dutiful?
If he doesn't, What should be the thought process that fuel Jon's morality? What would you like Jon's motive to be other than being the son of superman?

I would love it, if jon was sort of like lemillion aka mirio. His base philosophy should be "i might not be able to save everyone, but i will save at the very least _____ number of people". You know someone who has set a goal for himself to reach. The goal doesn't necessarily mean the end. It is just a check point.
He can also be an advocate for non-violence. Someone who refuses to punch to confront evil.Jon is part of the action genre. So, doing this will be a challenge. Might be impossible. Maybe,he could be someone who always chooses the path that leads to the least amount of blood shed.