Which is exactly why people who assert "Private Groups" = "Open PvE" are incorrect.
It's not even remotely the same thing. All Private Groups does is take the responsibility from Frontier to ensure a consistent gaming experience and put it into the players hands- the Admins of the PG.
Which, shouldn't even be necessary- but as I stated previously, given the constraints of the current system it's all that's possible at present.
That's my point, players who are arguing for FD to enforce their PG's informal rules need to realize that FD doesn't have the time or resources to cater to their individual group's preferences. It's just not a reasonable expectation, especially given the long list of game bugs that requires far more urgent attention from the devs.