Napoleon wants to "squelch" the incitation to protestation and rebellion. He would rather convince the animals that they have presently achieved their goals so that they can get down to the business of hard (and servile) work. Through Squealer, he would like for the farm animals to get used to the new "rules" and status quo of the community. which include unconditional and blind loyalty to the "cause" and acceptance of the new hierarchy of leadership.
By threatening them also with the eventuality of Jones returning, Squealer would condition the animals to accept the terms of self-sacrifice and even subservience without question. Most accept these terms (Think of Boxer's proverbs "Napoleon is always right" and "I will work harder." ) while others disagree. However, the dissident members of the farm don't get away with their "insurrection" and the political purges (along with some executions) start.