What, exactly, is subjective with "in real life, it's sad when people kill themselves"?

Someone's enemy could be happy if they committed suicide.

I'm sorry, but no. Suicide is sad, end of story. If someone is happy that someone else died, that person needs to seek immediate help. There is nothing good about a person taking their own life, not even if said person is a total monster, and unless we're going to invoke Godwin's Law, there isn't room for debate. Even then, it's still sad that someone would throw away their chance for happiness and redemption.