No, you don't get to customize your Mag'har as a Blackrock, Burning Blade, etc. You chose skins that once could be atributed to one or another clan, but all those clans became extinct once the Mag'har Clans were born as a singular Clan - hence why you don't find a "Shadowmoon Darkcaster" - it's all Mag'har Darkcaster. Hence why Geya'rah overlords over it all, while the Bronzebeard, Wildhammer and Dark Iron still have their respective leaders.
And yes, you are being ignorant of the lore. There's no mention of only Lightbound using the power of the Light.
We understood the meaning of the thread, we just don't agree with your headcanon.