Because he was old and couldn't get through to the moving target. Were his fights with Stewart or Schulz rigged too? Well, in George's favor the latter was, at least the result, for sure.
This is what I wrote after watching the first fight between Virgil Akins and Don Jordan, which I scored widely for Jordan: Let me begin by saying that - IMO - this fight was a complete sham. We know from their respective histories that Akins and Jordan were mobbed up, but this really illustrates it. Nobody can tell me that Akins was giving it a try in there. I've seen quite a bit of Akins against Vince Martinez, Tombstone Smith and especially against Tony DeMarco. And believe me, this wasn't him. In those fights his punching was crisp and hard. He fought back when hit and should have gone through Jordan like tissue paper. Instead, he flailed with big slaps. He cowered when hit (and Jordan was no banger). He turned in a complete non-performance, unless of course, his intent was trying out for Broadway. Not often I would say this but a definite tank-job.
Both Ali/Liston fights were fixed in my opinion. Otherwise I think a lot of fixed fights were judges/refs being paid off rather than dives. Floyd vs. Castillo I and Maidana I, Manny vs. Bradley I and Horn, Ali vs. Norton II and III, Leonard vs. Hagler and Hearns II, GGG vs Canelo II, at least one of the LaMotta losses to Robinson was a fix. Fritzie Zivic claimed to have taken several dives for the money.
Not exactly true just watch the videos. Ali beat the crap out of Williams he was like a punching bag. Folley he was catching with his best right cross over Zoras left throughout the fight the accumulation finally was too much with the last one. This was a signature for Ali the right cross over the left you see it in many of his fights most notably the Foreman fight. It was never one of them that stopped anyone Alis one weakness he was not a powerful puncher. It was always an accumulation of many that allowed him to stop people.
I’m not sure about fixed but it sounds like Liston had a lot of pressure on him to lose ie Black Muslim threats not sure about the mob and he may have just bailed certainly in the 2nd fight.
It wasn't a punch that stopped Liston. He caught him cold and dropped him. Sonny got up when Ali was done with his antics. All I'm saying is, this shot legit dropped Liston.
Watch the fight again. There were many opportunities where Morrison was in a corner, and George did not even elect to throw a single blow. No sense of urgency from Foreman to win the fight. He just looked like he was going through the motions.
Maybe he had conditioning problems. Maybe he had an off night. Maybe he was afraid what would be coming back. There are a lot of more plausible explanations than a fixed fight.