At the end of the video the presenter mentions that they plan to open source the language when it reaches a greater stage of maturity.
A code dump does not make it an open source project. Sustainable OSS projects are developed publicly.
That's probably why they're doing a code dump
The language spec, or the rendering backend code?
And even if the "complete package", if the "locally runable version" is an afterthought of the OnlineWebVersion, have previous situations like that not regularly resulted in *Paks wrapping an electron instance with some blobs under the hood?