I dunno. The episode was a little fast, that's true; but Fluttershy's behaviour seemed perfectly in character to me.
She simply has no understanding of how to deal with conflict in a mature way.
Either she just freezes, as is her usual, or she goes all-out — which might be appropriate when dealing with a raging dragon, but not so much when dealing with a rude shopkeeper. She is clearly incredibly skilled in working with animals, even potentially dangerous ones; and there was no reason for the bear, the cerberus, the cockatrice or the manticore to trigger her social anxiety. But when "people" enter in contrast with her, she has no idea of what to do.
Furthermore, behind her near-pathological shyness, Fluttershy has been established to have a rather critical and acerbic personality, I think: see her opinion of Rarity's dress, for example, or the way in which she behaved while discorded.
It was a very nice bit of character development to see her final interaction with Iron Will, in which she
finally managed to hold her ground without being unnecessarily aggressive.
edited 12th Mar '12 8:36:22 AM by Carciofus
But they seem to
know where they are going, the ones who walk away from Omelas.