I don't think that's what he's theorizing. He specifically enumerates expanding one's portfolio in the a.m. and contracting in the p.m.
Both of his propositions would have had inferior returns as compared to “buy and hold”. D.E. Shaw, where he was a quantitative analyst, is a HF strategy firm AFAIK.
The article is painful trying to decipher what he is trying to say. True, he implies this is on the day session. Hedge funds that day trade around core positions is perfectly legal & surely isn't market manipulation. He is blaming hedge funds for global wealth inequality, he should take this up with the Fed/ central banks.
Here's a slightly alternate version of the paper posted. https://arxiv.org/pdf/1912.01708.pdf I'll take a stab. My initial takeaway, is that he is saying that markets can be favorably manipulated by large enough short term players that implicitly collude, and he explains some possible methods that they 'could' apply to achieve this. He argues that as long as the manipulation is accomplished in such a way, that the overall drift is beneficial to overall market players (who most likely desire positive drift), then very few watchdogs will be likely motivated to investigate the manipulation. He starts by explaining one such mechanism that would benefit large players. Since the markets have a greater potential impact in the morning, a large player (or players colluding) could take a set of large positions in the morning and those positions would move favorably (on average) by some distance, call it x. If they take the exact opposite positions at the end of the day and close them out, the impact (movement) due to their closing out of those positions would be smaller, so that the net return would be positive because of the asymmetry of impacts at different times. Over time the cumulative net impact of these actions benefit those firms that have the buying power to move markets using this type of scheme. He goes on to argue that a more complicated favorable manipulation scheme could be applied at different times in the day, that might explain the overnight effects patterns across global markets. I know people get very passionate about manipulation topics, so I won't go any further. But that's a casual interpretation of his paper(s).