I usually just skip most of this Sunry part but:
Going LS, it is your responsibility to safeguard the republic, so therefore it is you duty to protect its soldiers, Sunry included. Regardless that he is guilty of killing someone on neutral territory, he was acting in the interests of Republic. And albeit that it is a terrible act, they are loosing the war, and it really doesn't compare to the brutallity that the Sith have shown. e.g. Taris.
And of course if your DS, you don't really care about the republic, so you would want Sunry, a republic confidant dead. And here, Ironically, to get him killed all you need to do is tell the truth.
All in all this is one of the better examples of Bioware writing.