Author here. One key difference between the Intel and TI layout is that Federico Faggin (who later created the Z80) brought silicon gate technology to Intel from Fairchild. This provided much better transistor performance. But it also provided a layer of polysilicon "wiring", which made routing much easier. (Kind of like routing a single-sided printed circuit board vs a double-sided board.) This gave Intel a huge advantage in layout. But even taking that into account, the TI layout is kind of terrible.
Silicon gate info: https://en.wikipedia.org/wiki/Self-aligned_gate#The_Developm...