First, in terms of advancement until First Class, I can't think of any of it that requires writing. In fact, I can't recall many Eagle required MB requirements that require writing, For example, Citizenship in the Nation only has one thing that requires writing--that is to write a letter to a your U.S. Senator or house member. The rest of that MB are all discuss, describe, etc., none of which require writing. Unless the specific requirement states to write it out,
In terms of making the jump, talk to different troops. Our troop has a variety of boys with processing and other problems.
I think the IEP is overboard and inappropriate. It is to be used by professionall educators who are trained in assisting with special ed. It is not an appropriate thing for a volunteer counselor to be bullied into agreeing to by fear of lawsuits. I'd quit first. That's not to say I'm not sympathetic and wouldn't accommodate those differences, but IMHO, the IEP and threat of lawsuits is beyond what I volunteer to do. It turns being a Scout leader into a legalistic nightmare. I'd find another organization to volunteer with.
I do think that you and prospective troops need to discuss this issue. In terms of the MB counselors, you and your friend can sign up to become MB counselors. Then, you could counsel your friend's son and vice versa, and avoid that counselor.