I believe he meant "only one book simultaneously". Not in the same general time frame. E.g. I currently have 6 books (5 fiction & 1 non-fiction) going but my eyes/brain are only physically reading one at a time.
That being said though, how can you take seriously someone that gets the "number of page turnings" off by an order of magnitude. Sony states 7,500 not 70,000. Another example of someone with a forum putting out erroneous information.