Divine Crusader- Castigation ability doesnt work on red names

[smouis]

I see that this has been flagged as a bug for, well literally years. I've reported it myself recently but nothing. I'm guessing there must be a reason it has never been fixed? Some boss mechanic that has come in since castigation was first introduced? I'm wondering if anyone has any ideas? If this is never going to be fixed (which it doesn't look like it will) why not just change the tool-tip to remove the damage to boss text?

Anyway, any ideas welcome (or an explanation maybe)!

cheers.