I think he means the latter. This makes learning the spelling harder because you have to learn each word individually, as you would have with hieroglyphs, as opposed spelling it out based on phonemes (that you would have learned from learning how words sound when spoken) and a limited alphabet.
That's not how I learned to read or spell in the 1970s. "Sounding it out" was the main strategy. You learned a few rules for how different combinations of letters sounded, and the exceptions to those, as you went along. But most words are spelled as they sound.
