Thrall isn't neutral. He is the representative of the Orcs on the Horde Council.
What you want to say is that Thrall gives out Neutral quests, aka quests that the Alliance can also do. But if an entire patch takes place in Undermine, are we seriously meant to believe that the Alliance should continue talking quests from Thrall instead of revisiting Mekkatorque?
Where is Mekkatorque? He hasn't been doing anything since BFA.