I suggest you read this on why objective morality is unscientific and quite frankly just doesn't exist in reality:
http://rationalwiki.org/wiki/Objective_morality
The burden of proof is on the people who claim objective morality is true. So far, no such proof has been provided, and everything we see in society points to morality being subjective.
So, when we all agree that morality is inherently subjective, then we come to the conclusion that saying Emhyr was objectively immoral is a false statement.
I am sorry but there is no ARGUMENT there at all, just a bit of explanation what it is, and it's possible origin. Also there is nothing about it being unscientific, because there is no argument that science somehow disproved the existence of objective moral truths.
Everything that is wrong with this article may be presented in this quite:
"Unless there is at least one type of killing that is universally considered to be murder, it cannot be argued that all societies agree that murder is wrong in any meaningful sense."
What it said is that not a single type of act is considered to be murder in every society. So what some societies consider a murder, others - do not. All right, I can agree with it. What does it have to do with the second part - therefore MURDER IS NOT WRONG??? Just because people may disagree that a certain act falls under a category of 'murder' (like we do all the time in murder trials), it does not follow that if an act falls under this category, it is still not wrong.
In general "murder is wrong" is considered to be TRUE BY DEFINITION, just in virtue of meaning of the words. Murder is usually defined as "unjust killing". The question is not whether this sentence is false. It simply can't be false because it is analytic (true by definition), similar to "all bachelors are unmarried". To use it as an argument against objectivity of morality is possible only for someone who never ever took even Philosophy 1.
By the way, this matter is much more complicated, not just an objective/subjective distinction. Something may be a matter of an opinion of an individual, or a group, or a part of social reality. Is police real? Sure as hell it is, just try to break the law. How objective it is? There sure won't be any police if all humans die out, for example. The same may be with morality. There is no need to ground it into a will of god, or some eternal abstract principle in Platonic Heaven. Morality well may be species-specific, and grounded in our shared physical and psychological make-up, preservation instinct, avoidance of pain and suffering, and so on.
Personally I am not objectivist about morality, I think it is constructed based on our biology and similar goals, but it is very far from it being subjective.