"Brutusk is out watering the bushes right now.
Stay close though, <player name>. He should be ready for our ride to Splintertree very soon."
Your only option is "I will check back with your shortly, Kadrak."
However, Brutusk is already spawned, and waiting any amount of time changes nothing. I have tried relogging, dropping and reacquiring the quest, and disabling all my addons, but I am unable to continue the quest (and thus unable to continue Ashenvale progression).