But my point is the "decolonization" bit. Fine, we work towards more accurate maps. Everbody (except the US government haha) wants that I guess. It's the identity politics part that still baffles me.

True, but he mainly seemed to have made a splash in the US with the colonialism angle. I don't think there was much of an outrage in either direction in Germany about that topic in the 1970s. I guess most people just shrugged and moved on because popular map projections already did balance relative size vs shape long before the 70s, and Peters-Gall was just a variation and not all that different to what was already established.