"Wallflower" has the connotation of being almost decorative, for show. Basically, he's calling out that they were active participants important to the discussio

"Wallflower" has the connotation of being almost decorative, for show. Basically, he's calling out that they were active participants important to the discussion instead of observers or accessories that the discussion could have been had without. It's not so much that they weren't shy, it's that they materially impacted the meeting. I think this was chosen to contrast it to an alternative method of diversity where many women are included but they are not as important. His thesis is not to optimize for "numbers of bodies" equal representation, but equal representation of influence.