>> "What sorts of speech will get me banned on Twitter? Do you think you've done enough to turn Twitter around? Why is Facebook so successful while Twitter looks to be in trouble?"

Those seem like pretty awful questions imo. He's not going to waste time listing off things that will get you banned from Twitter. He'll tell you not to violate TOS (in other words don't harass people). This should be common sense. With your second question he's obviously not going to say no. He'll give a standard PR reply. Same goes for the third. He's not going to talk up a competitor.