Eb has deep seated hatred for some things in the Dresdenverse. The White Court, and Kincaid. Also at one time his daughter believed he would help her, and the vamps with their plans... I'm wondering if Eb was a little more like Dresden in the past. That he actually had friendships with shady characters.
Betrayal is something that is difficult to forgive, and I suspect that either one major event, or a series of smaller ones led to Eb becoming what I can only describe as bigoted towards things that aren't human...
Maybe Eb is right, and Dresden is just naive about the world. Maybe there isn't a single non human that should be trusted.