"As if" is speculation and headcanon. Canon says it was the goblins, who then got Sylvanas in on it. Teldrassil also happens first. There are no indications the Alliance would be the first to use Azerite to destroy a Horde capital.
I'm happy the Undercity gets destroyed and not Thunder Bluff or some other Horde capital that belongs to a proper pro-Horde race.