I do like your analysis, Elizabeth.
Medium has to consider a million things at the back end before it releases results. And they did check all the boxes.
I also feel that they didn't choose anyone who has already been chosen for some or the other Fellowship. Because these writers have already been chosen / recognized by Medium therefore it's only fair that others get a chance.
Finally, the lesson every writer needs to learn is that the only validation a piece needs is of nobody. In the words of the fantastic Susan Sontag, 'A thing is a thing, not what is said of a thing.'
All my love.