No "not clear" means that you (and possibly even a judge) can't understand what rights the license grants. "Unnecessarily sweeping" would seem to be a better description here than "not clear" assuming their intentions were as they say.
The license is not really the place to explain intentions except where they place limits on rights but to define who has what rights. A blog post or a preamble about how the rights they receive will be used is more reasonable for that.
The license is not really the place to explain intentions except where they place limits on rights but to define who has what rights. A blog post or a preamble about how the rights they receive will be used is more reasonable for that.