As excellent of a fighter as Moore was I still think Louis could have won even at that late stage. It just might be a VERY hard fight.
Louis catches him at some point, probably times that uppercut when Moore crouches. Walcott is more slippery and unorthodox than Moore and has more power, I think Louis would deal with him easier than he dealt with Walcott in the rematch, not saying Moore wouldn’t have any success, he may take the first few rounds through boxing, crouching and countering Louis’ jab etc, but I think Louis starts to open up more and starts to walk through him a bit. I think Walcott was the better heavyweight than Moore and IMO it’s not even like Moore has any of the typical smaller man advantages over Walcott eg: speed, slipperiness, mobility etc that Louis didn’t already deal with against Walcott.
Moore's infighting, craftiness and power could lead to an early Louis KD in round 1 as Joe could be hit with a punch he wouldn't quite see coming at that age. However, Moore does not have Walcott's legs which were one of the key contributors to Walcott's relative success. He also didn't hit as hard as Walcott, nor was he as durable. Louis busts him up badly with the jab and stops him between the 5th and 9th rounds. This isn't going late but Moore will look really good at times with his counter punching.