O'Brien's face is described as "filled with a sort of exaltation.." Do those remarks in his explanation of reality seem irrational or insane?

O'Brien does seem insane and irrational to us. We are like
Winston, we have the capacity to think, and it seems O'Brien does too, but he is
choosing to believe in Big Brother.

O'Brien feels the need
to explain to Winston the reason for Winston being
there:

Shall
I tell you why we have brought you here? To cure you! To make you sane! Will you
understand, Winston, that no one whom we bring to this place ever leaves our hands
uncured? We are not interested in those stupid crimes that you have committed. The Party
is not interested in the overt act: the thought is all we care about. We do not merely
destroy our enemies, we change
them.

Further on O'Brien
notes:

 I
enjoy talking to you. Your mind appeals to me. It resembles my own mind except that you
happen to be insane.

These
two quotes prove something to me. Because I understand this book to be a dystopian novel
and because O'Brien calls Winston insane and himself sane, I believe O'Brien is
insane and irrational. Also, because his face
lights up at the opportunity to torture, that is irrational because no one should love
the opportunity to hurt another, that is not human.