He's not saying that's what you have to do. He's saying that has to be your reaction to the death of an innocent, if you want to remain in Fortress.
If you want to shrug off the death quickly and move on? That's great. Perfectly acceptable roleplay. But not the (currently) acceptable actions of a Maran.
The Immortal leader of Maran says that someone who is so casual about deaths of neutral sentient creatures does not get to be a Maran.
That leaves Bubadink with a choice. She could do some self-reflection IC, and try to see what the rest of the Fortress is saying. Or she could lose her shit, get angry and go deeper towards the "dark side". Both are perfectly valid roleplay choices.
You didn't take either option.
The problem seems to be that you think you should be able to do whatever the hell you want to do and call it your "role", without ever accepting any consequences for that. If you want to play a Magistrate that disregards the laws, that's fine. But if you get caught, you probably won't be a Magistrate anymore. And if you want to play a Maran that occasionally kills good mobs, that's fine.. but you probably won't be a Maran for very long. IC choices have IC consequences, you can't escape that. If you could, the game wouldn't be worth playing.