There is little plausibility to the claim that it is absurd to criticize anyone for being critical. Obviously, people must assess one another and not all assessments will be positive. However, there is wisdom behind the injunction against being judgmental. To be judgmental is not merely to assess someone negatively, but to do so prior to a serious effort at understanding.
The main conclusion drawn in the argument is that there is wisdom behind the injunction against being judgmental.