I think the essence of this thread is: People are idiots.
You can't take one event out of one competition and say "the top 5 are skinny except 1" so you have to be skinny. I'm sorry but that's just ridiculous. Why top 5 and not top 6 or top 10? What defines "skinny"? How do we separate out causation from correlation?
What you've done here is called confirmation bias. You believe skaters have to be skinny so you notice when they are and when they do well and not when they aren't and don't do well. I could just as easily say: Nathan Chen is skinny, was expected to vie for a medal and now he's in 17th place. See? Being skinny is a disadvantage! And it would be as meaningful as your post.
If we want to know the factor that weight plays, we'd have to study lots of data of ALL the competitors and decide if the ones with a lower BMI or lower body fat do better overall at all the competitions all the time after you come up with a reasonable criterion for what "doing better" means as well as what skinny vs. normal weight vs. overweight means. i.e., Do you use BMI or body fat or absolute weight or something else? You'd also have to figure out what variables to control for such as the amount of training they do on average.