Creating the Third Space

From the Gutierrez and Larson reading, it seemed that one way of fostering the Third Space is to ask questions without specific right or wrong answers, but that instead are open-ended, relying on student opinion and knowledge.  I see a problem, though, in that this resulting discourse must still be within the bounds of what is deemed "educational."  The student's question regarding people of mixed race in the South is acceptable because it falls within the proper sphere of discussion.  If it is still the teacher and/or the curriculum that decides what can and cannot be discussed, how genuine is this "Third Space?"  Does the student's question really count?  Or if the class had chosen to take her question and truly expand on it, there might still be other students who were uninterested and would start up another counter script.  Then what becomes the Third Space?  Is it created on an individual-by-individual basis?