“nefarious influence of the
Post modernism was a critique of modernism / structuralism.. With it is a “general distrust of grand theories and ideologies”.
Relativism is the stance that morals / beliefs are formed within a culture.
I don’t know how either is anti-philosophical.
Philosophy is relativist (general sense) by its very nature and post-modernism fits well within the critiquing and logic of much of what is done within the practice of philosophy.
You may have a beef with diplomacy.
Is it possible you follow Jordan Peterson? A critique from a libertarian site.