Set up a PvP group and advertize it like the PvE and oldtimer groups that are already out there. There might already be one. The tricky part is getting enough players in the group that you might actually meet some. With Mobius PvE I have only seen one person in the last week and that group is fast approaching 2000 players.
The number of players is the real issue in open, not just the Mobius group. Players are free to move to solo or private groups, any behavior a player feels is griefing (no matter what it is) will make them more likely to move away from open.
This forum post isn't going to convince anyone who feels "griefed" to stay in open.
The game has 4 forms of PvP.
1) Attacking a player who is wanted,
2) Attacking a player for their cargo,
3) Attacking a player at a combat zone,
4) Attacking a player for none of the above reasons.
You might not like number 1, 2 or 3 but the game is set up for them to happen in the open game mode.
Number 4 is what the OP is talking about.