IDC, based on what you posted I have some speculation of my own.
This is assuming that Bulldozer will be shown at the July 15th HardOCP event. I doubt H would be advertising that unless they were 99.9% sure they'd have something to show, as their reputation would take a hit if Bulldozer didn't make an appearance.
Ok, continuing on, here's what I gathered from your post.
(A) enthusiasts are a non-factor in decisions for launch dates and releasing information
(B) for AMD, the consequences of releasing information on Bulldozer then missing launch dates are much worse (basically lost sales) than saying nothing at all (temporary fluctuations in stock prices)
(C) they do need to keep motherboard makers involved, but wouldn't a simple NDA solve that?
Anyways, if AMD is willing to show Bulldozer at the H event, they're on track for the updated August release...if they weren't, then showing Bulldozer would just cannibalize sales. Is this a decent conclusion? I can think of two alternative explanations.
First, maybe the showing will yield little useful information (i.e. play some games running on our Bulldozer processor).
Or second, maybe they're targeting the event towards enthusiasts, thinking businesses wont pay attention to the results. (I don't believe this, but I suppose it's possible).
Just having some fun with this, I'm sure there are a bunch of holes in my argument.