Not with an unlimited population.
Nothing that I proposed precludes you agitating for a complete invincibility PvE mode as well.
I actually love mobius. Mobius forbids firing upon other players under any circumstances even in conflict zones when you're on opposing sides in a war.
The fact that those people are in mobius means that I don't have to deal with them.
I'd expect that such a flag would frustrate some pirates even more - as the target would be immune from destruction and could menu exit at will.
Some, not all. Besides, if I shoot out someone's drives and hatchbreak them they're going to spin off into the distance while I'm scooping the loot, I certainly can't be bothered pulling the whole bump-stop maneuver on someone who can disappear in 15 seconds. That flag would make pretty much zero meaningful difference for most pirates.
I only ever go for the kill if they fire back, in which case... their PvP flag would be raised because they fired on me. So no change there either.
Being incapacitated above a planet with gravity is still a rebuy. The flag would likely not change the outcome of an attack much, if at all.
Not every gank is carried out in a gravity well. If anything they're in a minority. So it's not perfect. It won't catch every possible method of ganking or griefing. But it will still catch
some which is a material improvment over what you have
now.
This is what I mean by absolutist. You freely shoot down
anything short of having complete godmode in the game. Even if something has nothing but upsides for PvE players, you still don't want it - you'd prefer gankers to have free reign like they do now? I mean, we can do that too, but you're clearly not happy with it.