I'll take a shot at this strictly from memory so if I'm wrong please correct me.
Salgado is a trained economist and wanted to use Photography as a means to show conditions that different peoples worked and lived in in some areas of the world. When he first started out he used Nikon equipment and bulk rolled Tri-X and then some Kodak Iso 3200 film. In the beginning he did not want to talk about the photographic process but wanted his prints to speak for themselves. As he became well known Leica made him an "offer that he could not refuse" and he started using Leica equipment and talked a little more about the process. Later on he switched to digital for probably several reasons and appears to be somewhat of a spokesman for the process. I do not believe he ever did his own darkroom or lightroom work. At one time a well known French printer did all his processing and printing. I think the majority of his work has been done on film.
That he is more commercial now is normal. Things change. I do not want this to detract from his work. Salgado made work with a strong impact at the beginning when he rolled his own tri-x and I assume he still is with whatever he is using.