I think Susan was probably raised by an excessively critical parent who continually shamed her for childish unintelligent statements to the point she broke and adopted that approach in her life. I've seen that connection between critical parents leading to a deeply felt shame that forces an overly cautious intellectual approach to life to avoid, at all costs, feeling that degree of humiliation ever again. I wouldn't also be surprised if there may have been a speech impediment during her earlier years. The tell tale sign is being a pathological intellectual 'front runner'. The value of the argument is inconsequential if the argument has a minority of support. Its a classic 'best defense is a strong offense' tactical approach that she uses like the childhood blanket to keep her safe.
Its seems like a sort of intellectual prison of fear essentially burned into her psyche from a young age, probably associated with extreme narcissistic parenting. Its really sad, and I recommend this be considered before indulging in the 'fish in a barrel' take downs that she becomes a temping target for. She will feel those in extremes of intensity, but she'll never let you know.
Sympathy should be considered.