In this case, The Dragon is basically getting his authority challenged. As such, he will probably need to make an example of them to keep the delicate balance of power in Vegas.
If the wizard is the one who was 'responsible' for it, he'd probably be the only one to be singled out for retribution. As was established in the Faerie War, lesser beings used in the course of a hostile action qualify as 'tools' and as such their actions simply add to the punishment inflicted on their master.
Were I in that position, I'd probably either have the wizard mutilated somehow to send a message to the White Council along the lines of 'You breached the accords and killed one of my men. I'm being merciful this time' or addicting him to the Red Court Saliva and then sending him on a suicide mission to excorsize The Cowboy or something.
And we could in turn use these events to hook the Characters in to the war and the crushing of the Red Court Vampires. The Characters being sent on some crazy suicide mission and they come back and they come into the vacuum of power, and in turn rumors happen that they were part of a set up by the white council to get the dragon in a place they could kill him
making a nice red target on all of the players