The key part to many scenarios where players are taken hostage, killed or executed is that there is an expectation of quality roleplay.
Of course, to many players being killed, captured or taken hostage isn't a pleasant experience for that character, but the situation should really keep you interested as a player too. As it's not always about winning.
The lead up to any event might be what forms that roleplay which you may or may not contribute to. But straight up killing someone, capturing them or taking them hostage without any good roleplay would be a breach of the rules in most cases.