So, obviously I don't want to sound ungrateful and I'm impressed that they put this together and made it freely available. I'm not sure that creative commons i

So, obviously I don't want to sound ungrateful and I'm impressed that they put this together and made it freely available. I'm not sure that creative commons is the right license though, since it doesn't require the LaTeX source to be redistributed if the pdf is (unlike the GPL or the GNU Free Documentation License). (They're providing the source on GitHub, but if interest in the project trails off and someone else forks it, the person forking is under no obligation to share the modified LaTeX). I can think of many sets of notes on the MIT OCW site that are CC, which I'd like to be able to modify and share but can't because the source is missing. Anyone else have thoughts on the right license for this sort of project?