Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

You just have to look at this plat to see that Babushka Lady would definitely have visualized some of the east face of the pedestal.

And she did, as she had to do: 

But, Mary Moorman was shooting directly across from the pedestal. It was a straight shot from her to Kennedy to Zapruder, so she would not have caught the east face and didn't.