Fighting is so skill and toughness based
That's why he does a tough hour long circuit. He wouldn't be 100x better off with an Olympic Weightlifting program. Strength and fitness isn't his weak point. He's doing something that builds the type of endurance he needs to fight.
There are a lot of ways to get in shape. It doesn't all have to be swinging a kettlebell and eating like a caveman. I'm not saying that Crossfit wouldn't be an improvement on what he is doing but what he is doing is an effective way to get fit. It isn't the best but it is effective.
To get fit all you have to do is work out hard, recover, and repeat.