Well, I've never killed the Don, but then there was no need, since I've never had a faerie ninja in the party. He is honest with you; that is, you pay his price and he gives you the real Astral Dominae. All he cares about is getting his cash.
Besides, I don't believe in killing people who are not overtly hostile (well, Crock may be an exception
).
Nightowl2