So, anti-semitism and racism along with his anti-democractic views.
He was a very important intellect in the formation of the post-cold war Army.
https://www.amazon.com/Breaking-Phalanx-Landpower-Bibliographies-American/dp/0275957942/ref=sr_1_2?keywords=douglas+macgregor&qid=1647477522&s=books&sprefix=douglas+mac%2Cstripbooks%2C66&sr=1-2
i am reminded that a couple of the key mid-century military intellects had anti-diluvian views that placed them outside the realm of acceptable behavior. JFC Fuller for example: