It's not hypothesis he's using good logic and he does a lot of research if you watch his channel. When you wake up in the morning your glycogen stores are depleted and you have no defences against catabolic effects. You've gone 7-8 hours without food and now you're going to go burn some more calories. And many people trying to cut are in a deficit already so that means they are much more likely to roll over into muscle catabolism.
I find it just brutal how little respect people have for old-timers in general in these modern times. It's one thing to say he's incorrect, it's another to call him a fat fossil. You guys need to respect these guys for the path they paved for us. Without these guys building up the sport and providing millions of people with inspiration, we wouldn't have nearly as much information on building muscle and manipulation of the body. Your grandparents fought or aided in the wars for our freedoms to enjoy this luxury recreational sport. People in many other countries aren't jogging on treadmills, they're jogging to find food.
respect in gyms and locker rooms - YouTube
There's such a little amount of respect for people in general these days, there's no comradery in the gym anymore. The guys in the golden age were all buddies and helped each other out. We ought to learn from their leadership. Enough with the win at all costs attitudes. Are we brothers in iron or out to destroy each other out and be enemies? We have this idea of being 'alpha' these days like this dick head guy that only considers himself and crushes everyone in his path, that's not what being a leader is all about. It's about helping out others and looking for reasons to complement and build up. The biggest form of 'beta' or weakness to me are people who destructively criticize and think of reasons to belittle others.