I'm too lazy to find the real study, but based on that infographic I think they increased training load for one group and maintained it for the control. That means they proved that increasing training works. They would have needed to provide an equal increase in aerobic training time in the control group to prove that lifting weights works better.
This is a lot of why coaching tends to be in front of sports science, it's difficult to design good studies, most of them use whatever random college kids they can recruit, and it's tough to normalize different types of training stimulus to each other.
Edit: with love from an Enduro nerd who put in a ten week block of picking up and putting down heavy stuff more than riding