The whole point being demonstrated is that someone who is obviously not plus sized in real life will read as plus sized when their silhouette is traced into a drawing. It doesn't matter if they are semantically skinny, thin, or normal, only that they are not plus sized but will be when traced.
So what is the dishonesty you're suddenly detecting? That Taylor Swift is actually not skinny therefore this illusion doesn't work? It's a visual illusion you're claiming is false, so visually demonstrate your counterpoint. Otherwise this is just throwing things at a wall to see if it will stick. After all, that outfit is clearly not loose fitting, as we can clearly see in the image.
Again, all this "confusion" and "problem" you're detecting are just neckbeards arguing about anything except the actual visual illusion because commenting on the exact right verbiage to categorize women's bodies into is more interesting to them than, you know, visually demonstrating why a theorized visual illusion does not hold.