First off, you would not have to be juiced to complete this workout. Some of you forget that leading up to a fight training is a fighter's ONLY job. Wake, up train, eat, rest, train, eat rest, etc...... While this type of regimen may be hard for some of us who have day jobs, it is not far fetched for a pro athlete to train like this. Some of you should have seen Randy Couture's workout protocol and nutrtional/ supplement plan. His was one of the most in depth and intense plans I have seen.
I work as a full-time strength coach for a university, and a part-time assistant strength coach for an NFL team and can say for sure that during certain times of year, my players training protocols look very similar in both style and volume to what Matt (and many other fighters as well) is doing. He is essentially doing a form of volume training. Doing this type of training for 8-12 weeks at a time would not lead to overtraining or diminishing returns IF one is taking in enough calories to promote recovery, and one is getting plenty of rest. Clearly Matt gets plenty of rest as he has nothing else to do but train. Therefore, he can nap or eat whenever he chooses, on whatever schedule he chooses that works for him. After the fight Matt has also stated he takes about 2 months or so off from that regimen to give his body a rest. During this recovery period he said he does single set circuit training 2 days a week, and limits his cardiovascular work to 3 days per week. So a protocol of 3 months max effort then 2 months recovery is pretty sensible.
Also, it is not all that surprising to see that he doesn't have a heavy focus on compound or multi-joint movements. I say this because more and more professional sport franchises are going away from those as well due to the high risk reward associated with them. While these exercise do have value, they are also very hard on your joints and carry the largest risk of injury as well due to the nature of the exercise (this correlation between these movements and injury is shown in multiple sports medicine journals). Now-a-days these athletes make so much money that the last thing they want to do, or the coaches want to do, is risk their health on their workouts. So avoiding these movements can be a smart precaution. Especially considering they can get nearly the same results without these movements by doing more stable exercises if they use the proper progression from workout to workout.