kboz, I think I understand where you're coming from. When I got into a poly relationship (we didn't know what it was called, we just did it) it was an opportunity to communicate with a woman directly and frankly in ways I never had before. Yes, jealousy is an issue and even when you say you're comfortable with her and another person, it's still there a little. Takes a lot of work and a lot of tears, too, but it's worth it when you come out of the woods on the other side, if you can.
I was in one relationship where I knew the other guy, and one where I didn't. It worked both times. I don't think it's that important. I suggest you let her establish a relationship, taking her word that she's safe, and ask to meet him later. I personally don't think laying a ground rule as a non-negotiable demand is a good way to do it. I prefer that tack that you can't and shouldn't control someone's behavior, just let them know what you want and what you may do if they do something you can't accept. That makes them a whole, separate human being with choices. I don't think you'll regret it if you do it that way.