* Ridiculous writing system: First, the term "ideogram" is no longer used, since it has the connotation (wrong, but older philologists believed this) that these symbols directly refer to an idea; "logogram" is the correct term.
The compound nature of Chinese characters make it possible for speakers to categorize a word without knowing its meaning! This can be done if they recognize the radical (<100 of them). For example you can tell if a word has something to do with the sea, even if you don't know it means "anchor".
* Writing system not phonetic: Any other European language than English would have formed a much better argument, since English is notorious for its haphazard mapping of mapping phonemes to the alphabet, partly caused by the fact that early printers in England were Dutch with bare knowledge of English.
One can argue that languages spread "hardness" in different aspects. Moser doesn't mention that Chinese grammar is trivial, to the point of nonexistent. Compare with, say, Greek grammar which has baffling complexity or Lithuanian that still has noun 9 cases! Some exotic native Indian languages have 10-15 noun classes (German has three, which we call gender). In pure writing complexity, some people rate Japanese to be even more complicated (with its three sub systems). Or for an older example, consider Mayan hieroglyphs.