T-Rex here puts Utahraptor into a moral and/or semantic dilemma. What T-Rex describes could be better construed as "assisted suicide," but it doesn't have to be that way.
Here's how this could work: T-Rex is terminally ill, and decides to live out the rest of his days IN SPACE. He accepts the fact that he is going to die, and makes the best use of his time by, I dunno, taking to zero-G flower arrangement. Some kind of hobby. Additionally, he tells Utahraptor to murder him at some indeterminate point in the future, when T-Rex still has several days left to live, at the very least. It will be a surprise! T-Rex will cower in fear, crying, "No, Utahraptor! I know I don't have much time left, but I'm not ready to go yet!" And Utahraptor shouts, "You wanted to be the first murder in space! There's no other way!"
Whether national or international laws apply IN SPACE is kind of murky.* It's entirely possible that an independently owned ship would be exempt from the law, the way that boats are when in international waters. The court would first need to decide whether the law even applied in this situation before they decided whether it constituted murder. Utahraptor's situation could also be improved by arranging a contract with T-Rex stating that there was some level of consent involved here. Then the headline would be, "First Dude Murdered IN SPACE! And It's Totally Legit! Nobody's Going to Jail!"
So long as there isn't a woman President, and people start referring to her husband as "the First Dude." Then that headline would be totally confusing. People would be all, "Oh no! Todd Palin is dead! He had so much life ahead of him!" And that would be terrible.
* - Yeah, sure, there's a Wikipedia entry on space law, but I don't have the patience to wade through that and figure out if it applies to murder. It's got all this junk in there about treaties and shit. Maybe if you pay me like a lawyer, at about $100 an hour, I could figure it out. Maybe I should set up a PayPal donation button...