I think one of the reasons the time limit hasn't come up much in discussion is that it's hard to envision the data/information/knowledge that we might have in a week that we don't have today. I don't mean to imply one way or the other whether this experiment will have meaningful results, just that it's hard for me to picture myself, in a week, reviewing the situation and saying "wow, now I know X, Y, Z." I mean I'm not sure what those X, Y, and Z might be.
On the other hand, the idea of an interminable ban on political discussion has many obviously salient implications, emotions, and such. A sort of half-baked analogy is that it's like lighting a tiny, contained trashcan fire in the middle of a nuclear reactor--it's not really a big deal but it's easy to see how it could trigger high-magnitude reactions from onlookers.