@TwEeD yeah, thinking about that while reading yer answer, I think this was a conscious choice from the author. If Rimuru had done this, he might have looked too cold-hearted to some readers, so instead of giving him the choice, it was left to the AI (Great Sage / Rapahel). On the other hand, this also shows how Raphael works (all numbers), but we kind of already knew that, so I think it was a way to not have to deal with the "cold-hearted protagonist" theme and keep the happy go-lucky slime with more ease.