The idea was inspired because I thought it was impossible to do this on the Win32 command line. Now that I know that it is entirely possible, I still think that the idea has merit for matching any quote character. However, the namespace clash with \Q makes it rather counterintuitive.
If you want to match any quoting character, \q isn't the way to go. [:quote:] would be more appropriate. But I think that the advantage is way too small that p5p would give it any consideration (rightly so, I'd say). Of course, if there would be a Unicode property for that group of characters, you could use \p{UNICODE PROPERTY HERE}.