And Loramus.And we can also note that those Illidari Demons were cleansed and therefore not typical.
In short....most Demon Hunters we see appear to have little or no trouble working with Demons. Just as Hunters have no trouble working with Beast.
You seem to have this preconceived idea that a Dmeon Hunter can never ever under any circusmatnces work with or ally with demons.
Let's assume that is true. In that case, Demon Hunters can never be a player class...because they're have to work with Warlocks.