There's a point when possessed Skye claims that the creature is in all their thoughts manipulating them. Of course she could just be saying that to feed the hysteria, but I wondered if it was intended as a kind of out, and implication that the Doctor would have been more successful, and the passengers calmer had it not been directly interfering. My guess would be that Davies deliberately left it vague, I think he thinks people really can be that unpleasant but he wanted to plant the suggestion that it wasn't entirely their fault so people could have a more optimistic reading if they wanted - but that's just a guess.