The article reads to me as reductionistic in the sense that provided QM could use real numbers only, it would not matter if aerodynamics or whatever at a higher

The article reads to me as reductionistic in the sense that provided QM could use real numbers only, it would not matter if aerodynamics or whatever at a higher, emergent level required them -- almost suggesting the other levels are not part of physics. In the same sense I did not see reference to General Relativity in the article -- as another fundamental ground in physics besides QM. Never learned manifolds stuff for GR, so I don't know if complex numbers become naturally essential there.