Moonbeam, TH has a point, although it was previously stated crudely. If the current form of morality is determined by a consensus of what is "best" for people (and then what is "best" is also determined by consensus, and on and on), morality is only pushed through power and manipulation. It is the immorality of subjective morality.
I am not saying that they are right to execute anyone, I am just saying that he has a point according to the views of many on here (who believe in subjective morality). Unless we want to force our subjective morality onto them as well. Which is unethical and immoral. It is a big circle.
Edit: of course, he could also be wrong according the subjective moralists b/c some might have created a belief that it is moral to force other cultures to do according to what we believe.