People align with their class interests. Class traitors are exceptional.
It's not surprising that someone with a keen understanding of the global north/south divide would do a complete full fascist 180 when they are shocked into realigning with their class (global north) interests. They understand that their entire body of work is still legit, it's just that their class interest is to now denounce it because they are horrified by the implications.
The truth is, the global south has no reason to be kind to the global north once the tables have turned. The global south has no guarantee of becoming socialist, only the potential opportunity. The only certainty of multipolarity and global south development is that living standards in the global north will sharply decrease as the disparity balances out, and that can only really happen via counter-imperialist forces that are opposing imperial market penetration.
Competent imperialists have to understand marxist analysis too, because it's the only lens of analysis that actually makes makes sense at different scales. That's why, when the mask slips, the liberal platitudes morph into zero-sum conflict theory materialist assessments on how to maintain the empire. The real evil of how to dominate markets is done via materialist analysis and disguised with liberal fluff.
How does a global north third worldist stay sane in the face of what might happen, what we've done to others, and what might happen to us when the tables turn? I don't know yet, it's scary, but I'm not going to become an imperialist cheerleader.
My concern is more what the impact of uncontrolled degrowth or sudden realignments of wealth and resources. The rich rarely suffer, but workers and the underclass in the global north might suffer badly if the pace of change is too fast to adapt to.