There is a lot to be learned from the design, even if you can't buy the SoC. Other chips may be compatible with existing footprints, and you could build extra features onto the current design.
Additionally, having a schematic would make OS development a lot easier. The information can be obtained from the currently published source code, or at $25 it would be cheap to sacrifice one to a hot-air gun and generate some schematics.
There is always a point, even if it isn't immediately obvious. People are curious and inventive and wonderful - they will surprise you! Just because you can't see somebody immediately being able to build this board, doesn't mean that the knowledge your work contains isn't useful, or won't be useful in the future.
Besides, you have no reason not to. Couldn't hurt, right? And it would make the open hardware community promote you even more.
Additionally, having a schematic would make OS development a lot easier. The information can be obtained from the currently published source code, or at $25 it would be cheap to sacrifice one to a hot-air gun and generate some schematics.