Make sure you asked him very clearly what he meant by "rule out." The term has two meanings... opposite to each other. It sounds like he meant what you think he meant -- "I'm quite sure that's not the problem." But the other meaning of the term is, "I think that may very well be the problem but I can't be sure right now."
I would also read Miraca Gross's article "Play Partner or Sure Shelter" (you can easily find it by searching the title) on how asynchronous development affects the development of friendships. It sounds like she wants something in her friends that most kids her age aren't really equipped to provide -- it's a useful skill for her to learn to socialize with them, but they aren't likely to be the sources of the friends who "fit her."
