Google Plus authorship are only meant for blogs and for journalists. Google will never accept the Authorship for any forums or q&a sites.
Google authorship will detect the article posted by a particular person
Now, guess, if A & B has Google Authorship and both users answers on a post, then who get the authorship?
If you hack the code and add Google Authorship, then only the asker will get the authorship (If missed by Google) and the real answer provider will be ignored.
Hence, it is not worth the Idea for a Q&A site.