I think the author's dilemma is the data is proprietary and won't be open or released unless it benefits the funds position. Fund managers will act on their information to profit before the market reacts or release the data after shoring their position and portfolio. If the data was open, analysis checked, and the information confirmed accurate then it probably would lead to a more efficient or at least accurate market valuation. But if it sits in a safe until no longer useful or released by someone else then we won't know.
I wonder if the author is thinking of groups that suspected the 2008 crash but either didn't raise the alarm and made bets on the outcome or weren't heard in the commotion. Any proprietary information they might have had could have alerted the public or something but there's always noise or incorrect predictions about the market and hindsight is 20/20. If their worldview is that private groups controlling information for private gain is bad, well that's already going on so this is just an extension of that.
I'm sure most funds have groups looking into data collection on top of modeling market results based on various inputs the data suggests. I'm sure most funds have some amount of proprietary data or algorithms to run against it, even if the info overlaps or they sourced from the same information like publicly available government released satellite photos. I'm sure that the market (mostly computer programatically trading) reacts fairly quickly to big players making less than subtle moves. There may be some method to deciding how far to go with certain information to not tip your hand or reveal information by inference. It's how the whole thing works already, and dropping into a mutual fund seems the best way to take advantage with minimal risk.