It's true the 2s complement wasn't always universal but von Neumann proposed it in the EDVAC report (1945). It was the IBM 360 (1964) which really championed it

It's true the 2s complement wasn't always universal but von Neumann proposed it in the EDVAC report (1945). It was the IBM 360 (1964) which really championed it. The PDP-8, 9, 10 and 11 all used 2s complement. By 1976 when this MIT AI Lab report was written, 2s complement was pretty standard. I think this is just the MIT AI Lab tilting at windmills. They had their quirks like wanting the world to call pixels pels well after the world had decided on the former.