Are alliance transfers to Sulfuras open?

WoW Classic Cataclysm Classic Discussion
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Transfer Restrictions and Free Character Transfers Now Available – Updated Sept. 9 - WoW Classic / Wrath of the Lich King Classic Discussion - World of Warcraft Forums (blizzard.com)

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They have not done faction specific transfers. They only do server specific. The reason it could be called “alliance only” was they opened Benediction to Sulfuras which was practically 100% alliance.