This was a tough chapter. It’s a punishing world that Bjorn lives in. She gets what she deserves for trying to kill them, but…it doesn’t feel good in the end.
She is a very sympathetic villain for sure which makes it great writing.
It might not have been necessary to kill her, but from a utilitarian point of view not doing so would be risky for MC.
MC might have been able to talk it out if he called her out on it, but with his popularity and fame that in itself is a risk.
The game does also not seem to require "PvP" so she lost her moral high ground as soon as you fight against "people".
Everyone is forced to play the game, so she was an innocent person only until she tries to kill somebody.
Not to mention you could end up in this exact situation where you fight another player without knowing.
At that point, you should be ready for the consequences of your actions.
And considering her gear this most likely wasn't the first time either.
Sure you could argue the moral implication of killing "NPC" characters if you do not believe them to be "real"
I would guess from the writing style she and a lot of people in their situation do just to cope with the whole thing.
However, that only goes under the assumption that the world they are in is a simulated world.
And they are not magically transferred to another world that just happens to be similar.
She would probably been killed once she was interrogated unless there was somebody to bail her out anyway.
So in a way, this might have been a mercy for her as she avoids torture and interrogation.
But it ultimately comes down to MC being extremely cautious of everything, from what we know of the game....
Which again, is for good reasons but might also be part of his barbarian characters influencing the player too...
That is just speculation for now, however...