There it is, that implication once more that Khan had betrayed him and not vice versa. He doesn't scoff, but leans forward the tiniest centimeter, and quotes Kirk's own words back at him with deliberate slowness:

"Please, sir. I'll do anything you want. Just let them live."

If Kirk imagines for one moment that Khan is anything less than a desperate man in that same position, that Khan will accept admonishment over his actions or hesitate to be so brutal in the future, he is sorely mistaken.