To Schwa or Not to Schwa

(Note on the SAMPA phonetic transcription｜SAMPA音標說明)

A Hong Kong Chinese blogger about English dictionaries and grammar whose views I often dismiss as too dogmatic points out how the first syllable of occasion being only /@/, not ever /O/ or /oU/. I occasionally do /oU/ and thought it a systematic option. Before I chalked this off as yet another uninformed post, I looked it up and it turns out I was wrong. None of the reputable English-to-English dictionaries (about 10+ of them) list /oU/ as an alternative. Well, this is perhaps the reason I have not unfollowed him.