Actually, the rebellious dwarfs seem to me to be Lewis' image of those people who, when times get difficult and uncertain, decide to look after only themselves and refuse to stand by their old loyalties. Once they learned that the False Aslan was a lie, most of the dwarfs (except Poggin) got all cynical about the true Aslan, and with that went their faith in the King and anything else greater than themselves. They became totally self-centered and self-concerned. Once they stopped living for something greater than themselves, they became capable of any atrocity, including murdering the horses in cold blood.
I think that whether Lewis intended it or not, the Rebellious Dwarfs are a picture of modern man and how he would respond to the trials of the end times. Once disillusioned, they quickly dismissed all that was good and noble as "humbug". Will we prove faithful in the trial, or will we follow that path of cynicism and unbelief?