The way he said it, I think he might have meant that 30% of Marriott's reservations come from their site/app. That's not evident from the 30% sentence, but it's suggested by the sentence that follows, where they seem to say that Marriot's internet persence was among the top 8 or 9.

It would make sense to me if only 30% are coming from Marriott's own websites, phone apps, etc. So many people (non-FTers who don't care or don't know they won't earn points / miles) use third-party sites. And then there's those business travelers who book through corporate sites.