From my understanding of the situation Gidgreen - the author of Q2A - wants to keep freedom of the code usage for whatever future use that may arise, including a possible commercial version (see http://www.question2answer.org/qa/5364/1-4-priorities-github-wiki?show=5364#q5364
This is more than fair enough due to the enormous amount of work put in such a development, I could not agree more.
The piece of code you mention is GPLed, which means including it in the core would make the whole thing GPLed.
Sure, Q2A is GPLed as well, but Gideon holds the copyright on it which leaves him freedom to distibute it the way he wants, which wouldn't be the case anymore with 3rd paty GPLed code in it.
Edit : this leaves you with the option to make some plugin based on the code you mention ...