a compelling reason would be the general near absence of prominently displayed hieroglyphs on the walls of chambers and passages.
(Khufu car touche is disputed, not prominently displayed in open general access space, only one instance of glyph in G1)
The earliest evidence of a hieroglyph is
In 1998, a German archaeological team under Günter Dreyer excavating at Abydos (modern Umm el-Qa'ab) uncovered tomb U-j of the Predynastic ruler called Scorpion I, and recovered three hundred clay labels inscribed with proto-hieroglyphs, dating to the Naqada IIIA period of the 33rd century BCE.
It would seem that on the basis of hieroglyph development, G1 predates it.
Unless we have very compelling reason/evidence to challenge this by stating that AE built G1 but for some reason did not use glyphs in it.