I don't have a good answer here. As discussed in What if it were you instead of Linus?, it might be safest to email the module's author directly, asking for clarification and seeking permission.

It starts to get murky if a module author accepts a patch from someone and that patch turns out to be legally suspect. Come to think of it, that seems to be more or less what happened to the Perl core in Professional Employees and Works for Hire. (I think it's happened to Linux also).