I'm pretty skeptical of their numbers as well. It costs calories to build the muscle in the first place. It's a snowballing effect.
That volume is good for keeping your body limber, but it’s not really exercise in terms of weight loss or cardio conditioning.
You may want to double check that math.
https://www.bikeradar.com/advice/fitness-and-training/how-ma...
Perhaps 500 calories/hour is a rough estimate. 100 miles @ 15 mph = 6.66 hours = 3333 cals or roughly what it takes to burn 1lb of fat.