I am a fan of open software, and also a realist. I think what he did is great. My only concern is that the source code in the book is gpl licensed (and not MIT or better public domain). This means for the student taking the class he technically is not allowed to use anything later in his work life (except of course he works for an open source company, which only a few do, bigger exception if the company uses the software only inhouse - but then he is in the EE department, so this means most students might work on products later).
Most coursework is (implicitly) proprietary, and that's not a problem, so I wouldn't expect an issue there. I suspect the key issue here is that the students are unlikely to be copying the material at a level which would qualify as a derivative work.
