The general point is that though equality may suit the imagination of an autocrat or an elite when the many are equal in subjection or slavery, the many themselves strive to become unequal. There is something unlovable about equality; so much so that it often feels like a condition accepted for want of a better one, and a consolation for those who cannot break out of it. If people cannot be better than those around them, they will lend themselves to the efforts of those who run their society to dominate other societies. And those who run society will always dream of plans to achieve a finer, more coherent or organic pattern of political relations elsewhere. One ingredient of imperialism is the desire of leaders to shake off the restraints imposed by democratic politics at home and treat other societies, especially non-democratic ones, as fit for the dictatorial imposition of democracy or some other rule. Imperialism provides the aesthetic intoxication of destroying and remaking customs and relations, rules and institutions. The leaders could not get started unless the many craved some of these same aesthetic gratifications and were willing to settle for vicarious triumph over others. Athens was democratic and imperialistic; America is the same.
I did not read the whole book, Patriotism and Other Mistakes, or even, with any vigor, the whole introduction, so I cannot really make a recommendation for the work as a whole. This point, however, seems to me to strike on two vital and related truths which are often ignored. First, the lower classes of society idolize and pursue equality only because inequality (i.e. dominance), while more desirable, is even farther outside their grasp. Second, even in societies where equality is enshrined as a theoretical ideal, the whole society, rather than merely the easily demonized master class, engages in imperialism as a way of grasping at the desired inequality which is inaccessible in an ostensibly democratic nation. Both combine to play with common notions of who the villains are in our narrative of injustice and whether or not even those who espouse the right ideology are fully aware of their motives.
There is, of course, substantial room for argument, but the approach and the conclusions in Kateb's quote demand engagement.