I understand what you are saying. However, what I see is that the far right, 6:00 is 24 hours after the morning exercise group. But only 8 hours after the later group. I would have liked to see the horizontal axis be time elapsed after excercise, not clock time.
And admitedly, I did not read the Materials and Methods section of the study, but it appears that the morning group had much more intense exercise. Why is this? Where the groups not matched? Was this double blinded?
I am not saying you are wrong, but there are so many variables here that IMO any meaningful conclusions are difficult.