The intonation graph may well be true, but I don't see how replacing the nut with a zero fret somehow cures the issue. I thought the Buzz Feitin nut, and the even crazier just intonation fretting some makers experiment with, would cure the intonation, purely by changing the string length between the nut and each fret for each string.
Will intonation of the first frets also not change with string gauge?