Not sure why the pose, though I wonder if the artist was maybe working from a photograph that would have hit the eye better as a moment in time. It's not a world apart from this 1949 portrait of Eleanor Roosevelt though, who must have been real fuckin' tired of holding that page just so if she was posing real-time.
Who knows maybe the artist had a really good photographic memory I have had fellow students in my art classes that could draw pretty well and realistic dispute only glancing at their reference once then started drawing with the only thing in view being the paper they were drawing on they were like human polorid cameras
"You painted the chair too?! I hate that chair! There's no way in hell I'm going to be immortalized in a painting forever with it. Paint over it so its gone from the painting. What do you mean 'it will look weird'? I'm paying you. Just do it."