In case it is just a delay and the release source code will be published soon, I'd also like to know the point to not make the development open. So anyone can comment, sent PR or participate the code in some way while the development is in progress.
This way of doing: publish binary then some days/weeks after publish code (all in one PUSH) is not the way opensource projects work.
People are welcome to contribute and the previous source codes were released with the binaries. Our development team are making so many changes to the code that by the time someone makes a commit or request the code would likely already be different.