I don't really know whats legal and illegal, but considering FD does already Shadowban people I assume its legal.They can't legally enforce private group rules, as those could literally be illegal and would get FD in lots of trouble, so that's not going to happen and expecting it to is not being sensible at all. NO company does that with their games, private groups in Elite are the same as guilds, units, teams in other games, and their private rules are NOT enforced by the developers, ever, for that reason.
There is no PvP/PvE flag, the game actively allows for and even encourages PvP when playing with others, Open or Private Group, doesn't matter, it's part of the core game. Bounties, CZ's, Power Play, all include PvP in them, and even Mobius' group isn't a PvE only group, it has PvP allowed with consent, except in CZs, where entering one GIVES consent implicitly. That's a big misconception, Mobius is NOT a PvE only group, people ASSUME that but it's not true.
FD doesn't offer a purely PvE option for multiplayer, it was never promised or offered, so why people demand it is beyond me. You want a purely PvE multiplayer online game, they DO exist, you should go play one of those, because that was never the premise of Elite: Dangerous multiplayer. You want pure PvE, FD has given an option, Solo, the same option promised in the KS from day 1, and the only option promised to be purely PvE from day 1.
Mobius' group problem lies in the fact that there is no vetting of the applicants, that's not victim blaming, that's a simple fact. This wasn't the first or even 10th time this has happened after all, and you can't just JOIN the group, you must apply and be accepted by the group's owner. First time or two it happened, ok, stuff happens, no big deal, let it slide, but...hey...man..can you start vetting the people maybe? 10th time it happens, dude, seriously, are you kidding me? You are STILL blindly letting in anyone who requests to join even though it's KNOWN that groups are trying to get in just to PK the members? There's an actual legal term for that, criminally negligent, when you KNOW something bad will result from your actions but you continue to do them anyway. Seems to me that I've heard a lot of people in the EU going off about how the various governments SHOULD have stopped any of the terrorists from getting into their countries since they KNEW they were trying to, and in many cases, KNEW they were there and did nothing about them in the first place. The acts aren't the same, not even remotely close, but the actual ethics and legal standing are exactly the same. Mobius knows this is a problem, he's not done anything to keep it from reoccurring repeatedly now.
Want to be upset with someone, that's the proper target, but no...people want to blame FD because...well...because!
No, I do not want a PvE Multiplayer I'm happy with solo, but I get where people coming from who want it and who would like to have it. And yes thats not what ED offers and people have to accept that playing Multiplayer in ED means giving an okay to be a target for all sorts of PvP including griefing in every form possible - as long as it does not involve cheating/hacking from the attacker.
But that is how it is does not mean one needs to be happy with it, complains are always valid and suggestion and asking for certain thing is valid too if it gets heard or not from the Devs.
Yes, at it is its Mobius fault. FD also does not give him any proper admin tools to control member tough. Thats why an offical open PvE would be a better solution, since no player all alone on his own has chance to actually properly manage a group of this size, mistakes are bound to happen.
Better solution under condiction we want a PvE mode of course, yes I know FD does not want it etc etc.
And no I'm not upset, but I do think its maybe not the best for the Game in the longrun if nothing is done. I could be wrong of course, but you never know that in advance.