Well Robert, we're going to have to agree to disagree on this.
While you don't believe the site can actually make it; I strongly disagree. You're asking for "organic growth" while the site exists in a somewhat closed or restricted environment, not receiving any search engine traffic and relying on members tweeting one question at the time to act as teasers for the site. I feel this is inappropriate or even border-lining unrealistic expectations.
That aside; I also feel a bit blind-sided by the communication (or lack thereof) from your side. No quantifiable metrics were given (you have 2 weeks to reach this target) - something I feel goes directly against the overall spirit of the Stack Exchange. You're given a goal - do this for this privilege, that tag, that medal. Gamification.
As for the information we were given, when the private beta opened. Well you know the email, but here's an exert:
Q: How long will the private beta last? A: Private betas generally
last 1-2 weeks while you prepare the site for opening day. Once the
site is populated with questions, and its initial scope established,
we'll open it up for public beta.
Q: How can I help the site succeed? A: During the private beta, ask
questions, answer questions, tag questions, edit questions, and vote.
Q: What else? A: The minute the public beta opens, invite your
friends. Spread the word via Twitter, blogs, and email far and wide.
Hang out on the site answering incoming questions during the first few
hours so that newcomers understand what a great experience a working,
popular Stack Exchange site can be.
While I can't speak for everyone else; I do know first hand how I read the above. We've been discussing questions (a lot), tags, good questions, grey area questions, no-gos and so on, and trying to reach out into all content areas involving Sitecore. Especially the ones who fall out of scope on StackOverflow which is decidedly meant for programming related questions. And while I don't have an exact count, I'd guess less than 30% of the questions we have would fit into the scope of SO. It might be tolerated there (when no one is looking) but they remain unwanted.
And while we've been discussing all of this, I was (and I know more were) waiting for the 2 weeks to be up, to open up the flood gates. Everyone "at the ready". Ready to reach the targets, crunch the numbers, get the traffic going.
And now you're saying; "Nope. Won't happen.". This is indeed disappointing.
You then proceed to argue; "Stack Overflow is good enough - 5.000 questions" and so on. Well I've been part of that effort for a good 7-8 years now - that comes to less than 1.000 a year on average. We have 110 in 3 weeks in a closed eco system. I could also argue; the very people generating that content on Stack Overflow are the people who would be participating and dedicating their efforts here instead. Or even - feedback I have received over the past 4 weeks while this has been going on - we would attract an even greater audience to this site than SO would ever see - simply because the community is more tightly knit.
I would ask that you reconsider this. The community is right now and over the next 24 hours demonstrating the commitment they have towards this endeavor. They - like me - were waiting for the promised and indicated public beta to really dig in. Don't let that misunderstanding stand in the way of making this a success.