By ready it means at least minimally engineered, not necessarily complete, not by a long shot.
The block explorer had some architecture changes recently and Sting is more on a research stage, to test the possible paths to follow.
Once a stable and solid base is laid out, even if it is not "there yet", then it will be "there enough" to be open for people to contribute, fork, learn or whatever else they might need to code for.
You are right, even if something never "gets there" it should be open source, but not before it is minimally built because it may be counterproductive.
Anyways, the release of the code is almost here and it looks beautiful.
On a personal note, I have learned a lot by reading and messing with the code of "dead" old open source projects, but I haven't learned much from open source projects that were not minimally developed at least to a point I could understand what they were trying to do.
Is it a bad idea to show the progress of the development on a public repository? Exploring those possible paths is also part of the work done on the project and can be useful.
It is not bad, thecommit history will be public like the code, in case someone wants to see how the development went/goes.
It is just about the first experience when it gets released (which I especulate in less than 1 week but don't tell anyone I told you that).
But you are not wrong, I understand and like your train of thought!