And again, Khan's actions were retaliation for Marcus's criminal actions. Marcus was ultimately the one who provoked everything that happened. He and Section 31 created the situation that led to Khan's violence. They found and awoke Khan, they made him mad, and they created the technologies he used to strike back. I just do not comprehend why you're trying to blame Kirk for Khan's acts and completely ignoring Marcus's far greater culpability.
I apologize, I jumped in between you and Cadet49
and so it wasn't clear what I was saying. I'm not ignoring Marcus' culpability. Blackmailing Khan into doing his dirty deeds is obviously illegal and immoral. Not to mention building a fleet in secret and attempting to precipitate war.
But, all that does not absolve Khan. Ultimately, it was he who chose to act in the manner that he has instead of finding a more peaceful way to settle the situation. This speaks to what he was capable of, the depths to which he could plunge and his dangerous nature. Kirk knew this. Note, I'm not blaming Kirk. He took a big risk in trusting Khan for however brief a time or to whatever small degree because hey, it's nuKirk: Leaps without looking and goes with instinct.
And also, it serves the needs of the movie makers to have more fun, action and drama rather than having nuKirk choose to inform Starfleet through New Vulcan or whatever other option he supposedly had.