ElegantDesklamp

You can definitely get Social Lion in a carrier. Unfortunately I closed my game and don't have replays turned on, but I got one in a Ranger in a Ranked game vs a Normandie (satisfies the other criteria as I was kiting around an island with them within 5km of me). Theory of mine might be that the achievement comes from killing someone aiming at you for an extended period of time. The Normandie was definitely aiming at me for quite a long time before I killed them since I was the only target in range.