When Squealer informs the other animals that the pigs are going to move into the farmhouse, he phrases it very specifically:
It was absolutely necessary…that the pigs, who were the brains of the farm, should have a quiet place to work in.
This is an example of a propaganda technique Squealer uses on several occasions. This technique has two functions; it plays on the popular conception that the pigs are the most intelligent animals on the farm and acts as an emotional appeal which makes the animals think allowing the pigs to live and work in the farmhouse will benefit everybody.
In reality, the pigs are moving into the farmhouse because they want to live in a more comfortable environment but want it to appear like a necessary move, not a selfish one. In the longer-term, however, this move separates the pigs from the other animals, making their rise to absolute power an inevitability.