This was taken very early in the day, as witnessed by the sharp northwestern shadows and disorganization in the crowd. I'd guess it was around 7am based on when the sun came up today here.
Using this map that utilizes the Washington Monument as a sundial, we can estimate the time based on the shadow provided by the monument:
Whether it was done on purpose to try to diminish the magnitude of the event, or a stupid mistake from the publisher.
It was packed to the roof with more than a million souls.