I'm glad to see that there's active development of fully free systems.
Freedom 0 is “The freedom to run the program as you wish, for any purpose” [1]. This doesn't mean that a neccesary condition or a program to be free is that everybody is able to do everything with a program; that's absurd and impossible. For instance, no program can solve the halting problem (https://en.wikipedia.org/wiki/Halting_problem). In the way it's written, it's very open to interpretation, but from the rest of the material on free software it's clear that freedom 0 referes to the absence of artificial legal and technical restrictions to run the program (Artificial in the sense of being anti-features whose sole purpose is to restrict usage, such as digital restrictions managemnt).
For instance, software which has the legal restriction that it can only be used with a specific operating system is proprietary, but software which is under a free license, has source code available, etcetera, and depends on a programming interface specific to an operating system is free. Likewise, the user interface of free software may demand physical capabilities that some handicapped people will not have, or knowledge that not everybody has. Neither of the requirements mentioned in this paragraph make software proprietary.
[1]: What is free software? - The Free Software Definition <https://www.gnu.org/philosophy/free-sw.en.html>
