I’m queer and basically a gender abolitionist so I am not disagreeing about the social nature of gender, but I think phrases like that are pretty reductive and depending on the context in which you hear it. You can think of just as many supporting examples as contradicting ones. Though, in my opinion we really don’t need to “show” that gender is a social construct, for many reasons, but mostly because so many people don’t care, and they think social constructs are good, actually.
Although I was unable to access the full article, the framing from the abstract seems to be: “Which is less human?” Followed be two pictures of cyclists. The question frames dehumanization as a given. I do not specialize in crafting these kinds of surveys, but it seems like “people dehumanize cyclists” is a weird conclusion to draw. I don’t know what the pictures were or if they were in color or silhouette, but I can imagine people are not used to seeing cyclists in safety vests and therefore it’s rated as least human, because it’s the least often seen kind of person riding a bike (at least in my experience). Just a friendly reminder to always look at the source, especially if it’s so easily accessed, since the commenter above was kind enough to link directly.