Still don't see Liston beating even that version of Ali, Ali would still get under Listons skin, beat him before they even enter the ring. Plus Ali still was fast with his hands , and may have hit harder because he planted his feet more as he began to age.
I think he meant: Ali may have hit harder than he did in the 60s. Bottom line swag, if a past prime Liston couldn't beat a very green Ali in 64, then a peak Liston is unlikely to knock out a supremely confident Ali in 74.