leaders are rot

[K K Rossokolski]

Guberman, your point about "negative" leaders is well made. Over the years, I've had dealings with too many of them!!.
But in a real sense you can take account of this in CS. Leaders add some fighting and morale value. Include them, and you get this. Don't use them and you don't. Simple. All other things being equal, a unit with leaders should over time perform better than one without.
I therefore doubt the need for leaders with a negative value as such. Faced with such creatures. I would escort them with an honour guard to the nearest map edge and hit the "Off" arrow.

Or use them as live bait. :kill: