Well, I guess if the honor system doesn't work then FD should look into providing a mode that doesn't rely on that, one where player on player damage is either not possible, or inflicts damage on the attacker, not the attacked.
It's happened a few times, and depending on who you are listening to it's a disaster, or something as rare as... something very rare. Kind of like PvP in Open.
Personally, I don't expect a player, a customer, to have to spend his time actively vetting people, no matter how trivial you say it may be. He's not paid to do that, in fact he has paid to play the game.
It's fine if FD don't want a PvE mode. Then they should just say so and be done with it. And I genuinely don't think Mobius players want 'revenge', I think they would just like to be able to play the game the way they want to. Presumably if they wanted to go around shooting other players they wouldn't be in Mobius.