As the Resident Controller for Western Europe, Mustapha Mond is one of the ten controllers in the New World. He is the possessor of works of Shakespeare, the Bible, and other confiscated novels. Thus, he is able to read and study the great works. And, as Controller, he is able to use freely and with impunity such words as mother and father. The maker of the rules, as he says, can break them too. And, so, Mond enjoys the freedom that the exiled have sought; but, his freedom is exhibited in a singular way, not in rebellion. For, Mustapha Mond knows that independent thinking leads to discontent, and discontent leads to rebellion.
Mustapha Mond chooses to live as he does in order to maintain order. For, it is only through unthinking consumerism that the society is stable. So, he deprives others of free thought, while he is able to retain unique views on the themes of freedom, happiness, civilization, and heroism. Incidentally, his dry delivery of his views contributes much to the satiric tone of the novel. And, ironically, in his intellect and wit, Mond is the character who must resembles Huxley himself. He has simply sacrificed his natural urges to learn in order to subjugate the people of the Brave New World.
You can find the answer to this is found in Chapter 16. Basically, the answer is that Mond himself was almost exiled when he was a younger man.
When he was young, Mond was a very gifted scientist. He was a physicist who was really making breakthrough discoveries. The problem with that is that the government did not want that kind of discoveries. They wanted scientists who would just take an orthodox "cookbook" approach to science.
So Mond understand the people who are exiled because he had the same kinds of impluses that they had -- he wanted to really explore and understand the world.