I think this sums it up. I have some insight into comic and horror/sci-fi conventions from acquaintances who appear as celebrity guests, and I've heard more than once that there seems to always be drama among the staff. You know this, clearly, yet you still enjoy going. So you must already have accepted it as part of the deal.
I'd say this. Don't approach the organisers. Either decide not to go to the con if you're concerned about a particular person or mix of people who will be there, or suck it up and take your chances without saying a word. No special requests, no gossip or b*tching. And telling the organiser of a con WOULD just seem like gossip/b*tching, as far as s/he's concerned. Someone at that level of responsibility isn't going to want to hear about that sort of thing, and they may well shoot the messenger. I see where you're coming from but it's all better kept to yourself.
[P.S.: I've been a celeb guest at a few conventions, myself, though not that kind. Organisers don't want to take any chance on ticking the VIPs off. If you complain in advance about someone else who will be staffing, even without their name(s), you run the risk of being shunned as a potential problem on the floor, rightly or wrongly.]