I agree with much of his assessment. ISIS played a major part in destroying the liberal consensus in Europe and the USA. People like to credit offshoring with the emergence of Trump, but I think the refugee crises played an underappreciated role in destabilizing the general political landscape, creating the conditions for Trump to emerge.
Social Justice also started emerging as a powerful political force in America around the time of ISIS. It is fair to say that terrorism, social justice, and right wing reaction all mutually reinforced each other during that period, transforming these movements into solid political identities that persist to this day. Nobody imagined that Tumblr tweens or 4chan would end up influencing an election, yet here we are today. The politics of the extremely online have become institutionalized, and are now being fought over on the streets.
The military implications are thus. All the fancy bombs and missiles in America's arsenal could not prevent the purely symbolic damage Islam did to the liberal world order. The vector of such attacks was primarily psychological, transmitted through television networks like a virus. Throughout time, the trauma inflicted by Islamic terrorism became a self reinforcing dynamic, sucking up ever larger amounts of resources and attention from society. This in turn is destroying the legitimacy of liberal democratic capitalism, which only invites even more of the same.
Modern political correctness, as a whole of society psychological control mechanism, was developed to contain and control Western populations that were losing faith in their governments over this spiral downwards. Although to most people it is just a burden, the ability of liberal states to suppress their population through times of austerity and social disintegration is obviously needed when traditional social bonds are being destroyed through demographic changes, technological acceleration, and economic decline. It is a topic that deserves further attention from a military perspective.