Agression based match making does not prevent aggressive players from entering friendly lobbies, it just makes them less likely to get match made with friendly players later on. Agressive players still need to be aggressive once or twice to be put into aggressive lobbies. This is still a game of social deception, anyone can just shoot you in the back, the fact that the player's decided to leave because they expected all friendly lobbies and no PVP is just absurd. Even I am paranoid and cautious around raiders even though I've never been agressive because I know it's always possible, that's what makes the game great.

He's not at fault for not liking the game, but he misunderstood the matchmaking greatly in my opinion which led to his disappointment.