Find an ally he may know, or even better, trust
Do you know anyone who knows Stephen Bennett personally? Anyone who knows anyone who knows him? (you get the picture).
What you need is to enlist an ally who already has his ear. If you can find someone, anyone, who he knows either personally, or by name recognition, who Bennett would be likely to listen to, and who agrees with our position, that is the ally you need in order to make contact.
When you find that person, ask for a meeting between S.B. and the two of you together, so that you are going as a committee. You can then play off each other when you talk to him, and while you might have ideas this other ally does not, s/he may have something to say to B. that gets through where your particular message does not. Try for a little committee of two people (maybe even three). But I think the key is finding someone who Bennett will listen to, and that means someone NOT already entrenched in gay activism, because that to B says 'enemy' right off the bat. His ears will be closed when he meets you. The ideal person is probably a religious leader of an affirming congregation who hasn't spoken out much, or at all, publicly (yet). Even better if its someone you know B respects in some way. Start asking people who they know.