I would heartily second this proposal. Releasing the firmware for the Sylphyo under an open-source license could potentially spur an ongoing community that supports development and growth of this great controller, and even potentially give rise to a re-birth of Sylphyo production.
Of course, there may be intellectual property issues that prevent this from happening, and the interested parties may have other paths or uses for continued development. However, open-sourcing the code does not necessarily conflict with those interests, as any downstream development of the open-source version could be incorporated into the original code and add value to that intellectual property ...
Here's hoping this could happen!