I assume you're talking about the point in the conversation when Jodi Dean said this. In US culture, while this is a form of address, it has a great deal of baggage. Like the term "sir," people sometimes reflexively object to it, particularly in situations like these, because it indicates a form of power or hierarchy that they are trying to downplay. Perhaps this is because of the leftist allergy to authority which hangs behind the entire New Left. On the other hand, in my experience, many women (and some men) object to it, particularly in the company of mixed age groups, because it indicates a difference in hierarchy on the basis of age. In this sense, it is sort of a joke, meant to say, "oh no, I'm not old(er)."
And just because someone is passionate (and in this case, articulate about her concerns) it doesn't mean she is bananas. Or, if it does, we could use some more bananas out there, particularly those like Jodi Dean.
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