How does Squealer justify the pigs' move into the farmhouse in Animal Farm?

You can find the answer to this question in Chapter 6. 
Basically, Squealer tells all the other animals that this move is necessary for their
own good.

The way that this is for the good of the other
animals is that Napoleon really needs to live in the house to be able to run the farm
well.  That will help the other animals because it will make their lives
easier.

Squealer also says, though, that Napoleon should
sleep inside the house because that is more dignified and the leader should have
dignity.

So Squealer justifies it partly on the grounds
that it will help the whole farm and partly on the grounds of how important Napoleon
is.