Just as it seems things are about to boil over or turn into a direct attack on Vol’jin’s ability to lead, he pulls out a trump card: Nathanos Blightcaller. Vol’jin already guessed that the undead were going to be a target of greater racism/criticism so he went to the one source no one wanted to – Sylvannas. In doing so he short-circuits Mok’tringar’s attempt to make him appear ignorant to what is happening and puts him on the defensive. Nathanos is Sylvannas’ bloodhound and he immediately senses the demonic stench of Varimathras on Mok’tringar. Though he can’t quite place it, it puts him on a very suspicious view – something Mok’tringar struggles to keep himself composed over.
The insult trading highlights that tension with Nathanos giving Mok’tringar a dose of his own medicine with the remark about “Gul’dan’s profession”. He also raises the stake to intimidate any who are involved referencing the Dark Lady’s attention to watch their reactions.