I wonder if NASA had already figured out the trajectory for Collins to return without the added weight of Armstrong and Aldrin and rocks?
Here is what Collins wrote in his book Carrying the Fire
"My secret terror for the last six months has been leaving them on the Moon and returning to Earth alone; now I am within minutes of finding out the truth of the matter," he wrote. "If they fail to rise from the surface, or crash back into it, I am not going to commit suicide; I am coming home, forthwith, but I will be a marked man for life and I know it."