What to do with Saddam if not to hang him?

Debating again on openDemocracy.net. I get asked by a supporter of the war:

Q: If you were against the war then in logic you must accept that Saddam would have remained in power. Is that a moral position to hold, given the kind of man he was and the kind of regime he ran ?

A: To tolerate the existence of oppression and cruelty in any form is immoral. As a human I accept that I belong to a species that is capable of great cruelty, and great stupidity. In that I do not spend every breathing moment in a never-ending fight against said cruelty and stupidity, yes, I am immoral. In that I am a human being, I suppose that I must be immoral in some existential sense.

But I do try to do my bit to further the cause of kindness and rationality. And i do this: http://www.greenhealth.org.uk/Index%20of%20Governance.htm