How to disable my website users to answer a closed discussion?

Hi,
Is there anyway that you will help me to disable my website users to answer a closed question as follows using anspress?
http://snowykyoko.com/caselaw/legal-answers-2/question/186/howdy-titus-here/

Mr. Raul told me that he can add this disable function to 1.4.3 version, could you do so asap please?
My customer prefers to use 1.4.3 for his website instead.