A fairy story is, by its very nature, simple and would certainly not be offensive. Should anyone misunderstand its intentions, they could surely be explained away. Orwell could then ensure his family's protection from scandal.
Being a fairy story also adds to the message Orwell was trying to portray - a simple message - be aware! All is not what it seems. Even those who purport to work for the greater good are overwhelmed by power. Plain and simple! Then, the true message could not be overlooked.
George Orwell is not actually his real name which is Eric Arthur Blair. He used the name we are all so familiar with due to the similarities between his novel and the Russian Revolution and so that his family would not be embarrassed by his socialist beliefs.
Publication was delayed until the end of World War II due to its controversial topic and a desire not to upset the Russians. You can gain much insight into Animal farm and all aspects by referring to enotes Study Guides and navigating to the summary and introduction.It is clear from these notes that:
Orwell made his political statement in a twentieth-century fable that could be read as an entertaining story about animals or, on a deeper level, a savage attack on the misuse of political power
Interestingly, the sub-title "A Fairy Story" was dropped by publishers when it was no longer considered necessary.