Anyone who has read 1984 understands that man is a product of a society that starves you for thoughtcrime.

The mind should develop a blind spot whenever a dangerous thought presented itself. The process should be automatic, instinctive. Crimestop, they called it in Newspeak. . . . He set to work to exercise himself in crimestop. He presented himself with propositions—'the Party says the Earth is flat', 'the Party says that ice is heavier than water'—and trained himself in not seeing or not understanding the arguments that contradicted them

And

Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity.

This to me explains his face and answer