1. Fasting does not lead to eating disorders. It might be one of the behaviors associated with eating disorders, but it does not LEAD to cause anorexia. ED's are extremely complex psychological processes, and most often have more to do with control than anything else (also distorted thinking/body image issues).
2. Having a master's in psychology doesn't actually make you knowledgeable about nutrition in any way, because it's diet/exercise/nutrition is not a part of the curriculum. It might be noted in a coping skills discussion, but there is no amount of formalized training.
3. What would your friend say about fasting for religious or medical purposes? There are several very legitimate reasons to fast that have nothing to do with actually having access to food. What about a 12-hour fast to have your fasting A1c checked? Doctors that I've known often write orders for fasting blood work.
4. Eating every four hours is not good for the mind. It creates obsessive thinking patterns. You'd constantly be thinking about food...what to eat, how to balance calories, macronutrients, etc, which actually can lead to disordered eating.
5. If you don't meet criteria for an eating disorder, a referral to an ED specialist is not only premature, it's also just completely obnoxious. Criteria for Anorexia include refusal to maintain a minimal amount of body fat (normally 85% of lower end of ideal body fat %), body dysmorphia, intense fear of gaining weight, restricting food intake, or serious over-exercising.
Stop trying to explain Primal to people, most either won't really get it or might think you're doing some extreme fad diet. Just tell people you're into "clean eating," meaning you cut out the majority of processed food and sugar. You eat whole foods and try to get a reasonable amount of exercise. Most people will understand that without thinking you're crazy.