I can only assume there's some larger disconnect at this point.
If you are asking me to compromise on my position about ganking being griefing, I cannot. Because that is a personal values/morals code. You can no more demand a compromise on that than you could if you demanded I don't view murder as being wrong. That is an ethical debate, not a game-mechanics one.
But as far as methods to curb ganking? I have TOTALLY compromised over and over again on that while you and others have not.
The issue of your or my definitions of griefing would seem secondary in a sense, because the point of contention is more broadly what people enjoy about the game and how they think it should be played and it is, of course, going to be pretty subjective as we've seen. The discussion would be better spent on how to cater to the broadest range of E : D players' tastes with the fewest number of toes-stepped-on... which I think many have been trying to do, to be honest, but if we're going to get into semantics:
You asserted earlier in the thread that a player shooting another player on the opposite side of a CZ counts as 'a d-bag ganker':
You're grinding on some Spec Ops in a CZ and some d-bag CMDR starts trying to gank you
Now if you assert that killing someone in a CZ = ganking, and that ganking always = griefing I'd go so far as to say you're flat-out wrong. It's legitimate, systemically supported gameplay. If you don't like that gameplay I think it's perfectly reasonable to go to a private group. I also think that you shouldn't be instanced with other people who don't share that preference, because their game will be weakened by an invulnerable player flying around them directly countering their efforts. If I share an instance with a player pledged to the opposing side then it's weapons free as far as I'm concerned and I would genuinely hope they'd feel the same regardless of our relative power spectrum. This includes situations in which I'm the losing party because, and this doesn't get said enough, losing can be fun too! (I honestly didn't even mind being ganked when I started, but I can see why others would, and begrudge no-one their safe space).
So, if multiple players are engaged in trying to move a
game system in opposite directions, face-to-face,
not shooting each other as part of a limited and private social agreement is one thing but not being
able to shoot one another at all with no recourse is immersion breaking and ugly game design.
This is the most stark and obvious example of player opposition and you've already written it off as 'griefing'. The second stage, the extent to which stakes exist beyond a single CZ instance into the wider game, like Powerplay, like the BGS - stakes which many players take incredibly seriously - is seemingly a write-off to you as well:
There's absolutely nothing tying me to those "sides". There's zero mechanisms tying the player commander to the NPC factions. I can fly to any system I want, and join any "side" willy nilly back and forth. There's no storyline. There's no deeper character progression. There's nothing there.
The fact of the matter is thousands of people think otherwise, and
play otherwise. So. Y'know.
For many people the strategy layers of the game being pushed a) by random players who aren't aware of it and b) by opponents in private groups without the opportunity to intervene can be frustrating, as it can seem like it robs the game of potentially interesting emergent encounters. Honestly, people just have to put up with it; even aside from private modes there are also just timezones and p2p to consider, making it impossible to meaningfully oppose those who don't want to be opposed. I'd say probably most groups are resigned to it... Every now and then however you do get to interact with someone directly adjacent to some legitimate gameplay stakes, and these are often very exciting moments. The proposed flag system would be actively detrimental to this, creating an environment where you're able to see players acting against you but not interact with them. Again, if you don't care about this, you could at least acknowledge that some do, in the same way I acknowledged that you don't want to be shot at.
Now, I assume I've already lost you by this point based on your previous dismissal, but, given the above points: if players of your preferences can already create a space where you're instanced only with friendly players who have agreed not to shoot you, and if you're otherwise able to block players in Open you don't want to be shot by, it seems to me that you already have a decent amount of recourse to solve your issues without the flag system. Players who
do take the strategy layers seriously and
do enjoy emergent conflict or danger would have
no recourse with the flag system.
It would be fairer in my opinion, if anything were to be changed at all, if Fdev were to make an "official" Mobius mode, but again there are plenty of reasons why they probably won't do that (mentioned some in this post:
https://forums.frontier.co.uk/threads/pvp-flag-in-open-play-for-nopvp-players.565981/post-8969763)