1) Do you think this is accurate?
For me, no matter what the activity is - purging, exercising or restricting - the fact that you are "trying to get rid" of something, trying to "cleanse" your body, trying to "burn off calories" obsessively is a mental problem. It doesn't matter WHAT you are doing physically, it's what happens in your head that is disordered.
I've told my friend about non-purging bulimia and compulsive over-exercising but I don't think he can accept it...which also makes me wonder, "How do you convince someone close to you that they might have an eating disorder?". It's very difficult and most people are in denial until the tragedy already happens; they fuck up their metabolism, they crash, and their eating/exercising habits become unsustainable.
2) Have you ever talked a friend into getting help for their disorder?