I agree with your final revision to the documentation string. The doc text truly doesn't make much literal sense. And unless one has perfect Perl Monk karma, I don't see how one can easily intuit the difference between scalar context in a looped vs. non-looped context. The purpose of documentation is (presumably) to help those who are not yet experts. In this case, I humbly propose that the documentation fails to adequately and properly document the behavior in scalar context.

Also what happens when glob is called in a function that is embedded in a loop? Either way I can imagine challenges. If it is still considered in a loop then the behavior for example of glob used somewhere deep in a module funciton would vary depending on whether it was at some level called from something in a loop. On the other hand if calling it from a function that is embedded in a loop behaves differently from calling directly, then again you have an odd behavior where simply wrapping 'glob' in a function call would change its behavior.

To me, this still seems quite flaky and upnredictable. At a minimum, it deserves copious documentation to explain the behavior and potential issues.