Zone focusing, a small aperture, and flash are the thing for something that is really moving around, but many of these shots are of candidates giving speeches, moving enough that it's helpful to be able to check focus with the rangefinder, but not so much that zone focusing is necessary, and he's using mostly wide apertures to isolate the subject.

On the other hand, that picture in the article shows the lens tilted way back for even tighter selective focus, so in that case, groundglass focusing is the only option.