I might agree with this if the primary driving factor behind eating disorders was actually weight. It's not, it's power and control. People with eating disorders generally feel out of control in some aspect of their life (very frequently occurring in loved ones of terminally I'll patients etc.) and take to controlling their weight, food intake etc to supplant their lack of control somewhere else. If that lacking control is in the sport then I could see it, but that's not the same caliber of control issues you'll see with most eating disorders. Some even happen in reverse, it's not unheard of for a boy with an eating disorder to get into wrestling because it's acceptable if not expected (during the season) to be over the top about weight control, so they don't have to hide as completely as usual. It's another control.
All that being said, I've been around Cheerleading for several years and while there are people in every walk of life with these issues, I've not seen a lot of girls that look like they're struggling with this in a clinical sense...yes, they may be stressed about weight but I'm talking about clinical eating disorders. My thought toward that is that people with eating disorders are weak. Weak folks can't stunt or tumble so someone with a true and extended eating disorder is not likely to be successful. You can't look like Cheer ABletics when you're starving yourself. And someone with true eating disorders is also not likely to want to join a sport with half tops, not because of the weight but because they'll call themselves out, girls with prolonged eating disorders are hard to miss.