As much as I would love to release the source code early, if I did, there
would be nothing to sell! Also, it wouldn't add much additional proof of the
software's existence.
The FSF supports selling free software - the GPL was designed with this in
mind: https://www.gnu.org/philosophy/selling.html
It's a lot like crowdfunding - except when you use Kickstarter, there's
always the chance that the project might fail. With LibertyBSD, you can be
certain that the product you are paying for actually exists.