Cardio is almost everything in a fight.
Probably he is losing weight like Thor did.
The article stated that he was going to fight at an open weight above the 265 lb. limit. Even if he loses weight, his cardio isn't going to be but so good just because of the amount of muscle he carries.
That's one of the reasons I said that I hope they do this wisely and match him up for just fun fights and possibly with other people in similar situations to him.
Mariusz Pudzianowski is a good example of a strongman turned MMA fighter that can be okay to watch when matched up appropriately, but then I feel bad for when they match him up with people that are more experienced and in better conditioning for the sport.
I think its cool that some of the guys want to try, I just think for their own health and safety they need to be matched up against people with similar skillsets and not put against people that have been training for this most of their lives.