I am not a developer but consider this: this is open source. If the devs really work on particularly valuable features it would make sense for them, to NOT put it on github unless finished.
When it is on Github, even in unfinished/early version, every other competitor could steal it and complete it themselves. If I was workign on a project like that, I would keep everything local until completely finished, e.g. delay uploading into Github until the last possible moment.
This still not explains why so little code work was published until now (according to OP), though.
I am not concerned about the SC copy, but the relatively modest changes are. I wish you would address all the points OP makes, not just the SC fork (e.g. ring size, starting but not using obfs4.exe and so on).
XSPEC now also have steady development funding and will hire. The community will make sure that XSPEC will last for years to come and with a solid dev fund we will have the resources to develop the project. The team is together and strong and nobody has left for anything else. I am working on something auxiliary that will benefit XSPEC in the long run but can't say anything right now.
That is extremely bullish if true.