I think that the answer here is going to be a complex one. Initially, it should be noted that the massive rejection of the work from editors is reflective of the social attitude at the time. There was a glorification of Russia at the time of the work's composition. Stalin and Russia were seen as vital elements in turning back Hitler. In England's case, Stalin and Russia were instrumental in preventing a full out attack on England. The prevailing social attitude into which Orwell writes is one in which the Soviet leader was praised for his standing up to Hitler.
Yet, it is precisely in this social attitude that Orwell's work becomes significant. When Orwell writes the book, it is designed to offer a rebuke of the Soviet leader: "I thought of exposing the Soviet myth in a story that could be easily understood by almost anyone and which could be easily translated into other languages." An argument could be clearly made that Orwell is reflecting the ideas of the society in which it was written. A social and political order that encourages freedom of discourse and freedom of thought is the exact opposite of what Stalin constructed in the Soviet Union. While the contingent condition of the time period is one that praises Stalin, Orwell realizes that the basic tendency of Western government is the ability to voice dissent and offer political critique. It is in this spirit that he composes his work. Animal Farm reflects the idealistic values to which British society is intended to strive, a vision of what can be as opposed to what it is. Orwell's work reflects the values of what can be in light of the political expedience of what is.