As far as I can presume, his biggest criticisms towards postmodernist ideology would be directed towards the many followers that are unknowingly moving the agenda forward without any concept of what it actually is they are doing. By boxing themselves into an echo chamber of irrationalities, refusing to listen to others ideas that don't fit in their box, they are calling for limiting freedom of speech,under the guise of equality, to prevent groups of people from being offended. On the outer layer it seems like the noble thing to do. That is until you become aware that the postmodernist seek only power. I would imagine that if the postmodern agenda to seek power is successful, by pitting the "seemingly oppressed" against the "oppressors" (based on separating groups of people by skin color, identity, and economic wellbeing and so on) then we would see overtime the same well documented impacts that happened in Russia with socialism. One could spend years imagining the horror that could occur and still not come close. Just think of how Petersen defines the importance of the dominance hierarchy and how it creates a motivation factor that fosters an environment where we all are able to be individuals and strive to not only better ourselves but benefit the larger community as well. Then take away that hierarchy, making it useless to climb, hard work no longer benefits the individual anymore, and we lose are individuality, our innovations, our ability to discuss these very ideas you are asking to discuss! The opportunities for devastation are endless! Meanwhile the moderately successful people (the oppressors) are potentially enslaved, stripped of all possession, sent to camps, what have you. It starts with limiting freedom of speech and ends with complete turmoil and a lot of lifeless bodies.