I applaud your willingness to balance the interests of various groups of people on the site, and the site itself. For this reason, I would like to work with you to craft a solution that will lead to a "win-win" situation for everyone involved.
What I propose is that instead of having only two categories of questions, open and closed, that we create a third category, deferred. The third category would consist of "basic" questions that are fundamentally suitable for the site, but are not optimal for a site in private beta. That is, they would be "hidden" during private beta, and released upon the launch of public beta.
The reason I propose this is because of the nature of "commitment" (to private beta). I'm speaking as someone who has six fulfilled commitments to private beta on Stack Exchange. That is, someone who signed up for private beta is expected to make at least ten posts (questions and/or answers), during private beta (with a "grace" period for some days after the beta goes public). There is a meaningful penalty elsewhere on SE sites for NOT fulfilling commitments, which is why I'm being "sticky" about this matter. Perhaps you (and others) didn't realize this, but there is something of a "publish or perish" dynamic here.
A site typically signs up 200 committed members of which normally about one-quarter, or fifty actually fulfill their commitments for ten posts, thereby generating at least 500 posts, lets say 200 questions and 300 answers in the first 30 days of the site. Put another way, I have received a loud and clear message that one would be doing the SE site a major disservice by not fulfilling the commitment, one that would be offset by posting only egregiously bad (not merely mediocre) content.
Bottom line, I am willing to work with you and others on an arrangement that benefits the Earth Sciences site, as long as my own interests (and ultimately Stack Exchange's interests) in fulfilling my commitment are protected. Specifically, I am willing to have my weaker posts "deferred" until public beta, in the interests of a providing a higher quality private beta, as long as I get credit for my posts' fulfilling my commitment upon the launch of public beta.