Are you saying that discontinued products should be made available for free or that they should be open-sourced?
I can't speak for clang_jangle, but I believe that software should be required to ship with buildable source if it is to qualify for copyright protection. It would be the software/copyright analogue of the disclosure required for patents. It would go some way to mitigating the problems caused by copyright as it is applied to software, abandonware being one of them.
Should we bundle brushes and paint with every painting in order for it to be a copyrighted work?
It appears that PL/I (and its dialects) is, or will be, the most widely used higher level language for systems programming. -- J. Sammet