You are saying if you don’t play the way I want you to I will black list you. So yes this is being a tyrant.
If you said you would black list people who don’t use DKP in their guilds I would say yes you are being demanding as well.
I really have no problem if you have rules within your own guild as that is part of a guild. But you are trying to dictate how everyone even people outside of your own guild can play the game.