Hey~
You are a good friend to be reading up on her son. You are also a good friend for not being pushy. If her son was recently diagnosed, she's going through a great deal of emotions right now and some people will just disregard any attempt at help at this point.
First, 2 is not too early to be diagnosed. My step daughter was diagnosed at that age.
Second, go ahead and show her the article, but don't push.
As you mentioned, autism spectrum disorders affect different people in different ways... therefore, the treatments will vary in effectiveness. My husband and his former wife tried every new thing on their daughter in hopes of a "miracle pill." One treatment at the time was high doses of vitamin C. It was said to work on many children, but didn't work on her.
My step-daughter is now 20 years old and has a terrible diet as well. She would live on macaroni and cheese if we let her. She's old enough to understand that if she doesn't eat what we give her, she doesn't get anything else. She loves berries, so we are sure to give her strawberries, blue berries, and any other berry we can find regularly. We also let her eat cheeseburgers, pizza, and all her favorites as well, but she also gets chicken, pork, beef, and veggies. She doesn't like it, but she eats it. It's healthier for her.
Parents of special needs children often allow much more than others might think they should. I believe there is a certain feeling that they just don't have many pleasures in life, and if the parents can make them happy, they'll do it because they would do anything for their children. I know... it may not be the best thing, but I believe that is sometimes a parent's thinking. Just keep that in mind. Your friend is hurting and dealing with a lot right now. Be gentle. Show her your love and support. Be well.