It sounds like it’s largely about good sportsmanship and deciding on an OOC level to poison an IC victory of another player so that it’s a misery to actually engage with it. It’s not really about “pacifism” so much as someone just not being a good sport and setting out to make other players’ experience worse because they didn’t get what they wanted how they wanted it.
Although it definitely does bring up memories of the time when we invited a new player to our post-apocalyptic Shadowrun game and when we didn’t go along with what his character wanted, he suicided that character, then made a new character who was an “avowed pacifist” and ruined our attempt to ambush some targets because “he wanted to stop the violence”.
We uninvited him, obviously. Sometimes a person just doesn’t fit with a group or isn’t capable of playing nicely with others. I suspect it’s less about it being PvP and more about just some people don’t get that it’s obnoxious to set out to ruin other people’s experience because things didn’t go as you wanted.
