The soundest advice: NEVER negotiate with terrorists.
King Obamagabe should have went on national TV and said the following “I have witnessed a brutal decapitation of one our American citizens. Let the world know that America does not back down from a fight and this type of despicable evil. The full weight of the US military will be thrown at these radical, murdering 6th century madman. I have ordered today the US Marines and the 82d and 101st Airborne Divisions to prepare for an extended deployment to Iraq and Syria. For every American that is decapitated they will decapitate two of the enemy. We are now in a state of war and I have called for a joint session of Congress to legalize this action. Thank you very much and God bless America”!!