The "hostage taker" analogy is a terrible one. There is no situation in law enforcement where police are allowed to kill a suspect immediately on sight, regardless of circumstance. When Obama added Anwar al-Awlaki to his personal "kill list" (a decision he said was "an easy one"), it became open season on al-Awlaki.
For an example of why officers can't just shoot suspects on sight: in the Dorner manhunt, LAPD shot at a truck just because they thought it fit the description of Dorner's, and ended up shooting innocent people instead.
Which means that police actually does shoot on sight, despite whatever instructions say. And in most cases, no attempted murder charges follow if they shoot the innocent.
I really like this analogy, and I'm going to steal it. It really drives the point home.
I do have to be a pedant though and point out that "fatwa" just means "legal opinion" - in common parlance, we use it to mean "death sentence" because we think of people like Salman Rushdie (whom Khomeini sentenced to death under a fatwa in 1989).
If anything, this makes it worse - at least Khomeini had to provide some legal justification for his decision[0], whereas Obama has refused to do even that.
[0] A legal justification under Islamic law, which many would agree is itself arbitrary, but that's still marginally better than "trust me, it's legal, but I'm not going to tell you why".
I was aware of that, Shia canon law is a pretty fascinating system. If you can figure out a way to keep the pithy nature of the comparison while improving the accuracy, I'm all ears.
Eschewing the rather more obvious argument that the US military's policy of unannounced drone strikes in ostensibly neutral countries could prove counter-productive, we've got this rather absurd line of argument that someone who has to all intents and purposes publicly declared war on the US, is well beyond the reach of domestic law enforcement and actively encouraging militant attacks on the US military deserves due process and a civilian trial because he was born in America.
But he's happy to endorse his fathers' proposal to reward rather less surgical strikes by dubious third party bounty hunters without any more semblance of due process, provided the alleged terrorists aren't American.
It's not meant so much as an analogy, but an example that shows the rule of "the government shouldn't kill people without a trial" not really being a rule.