If you disagree with the eligibility determination (e.g., they find him not to have an eligible disability, and/or not to have educational impacts from it), you may reject the finding, and then either request an independent evaluation, sometimes at district cost, or on a sliding scale (depends on the state), or you may appeal up the state DOE chain. (You may request one independent eval for each time the school district evaluates your child.) Your state may or may not have deadlines for when such an appeal or request must be made. That information should be in the parents' rights/due process brochure which they were mandated to give you at the beginning of this process.
I apologize for not remembering the details of your situation...but unless you have other reasons to believe the school is unduly antagonistic, the language of the meeting invite you received does not suggest one way or the other how the meeting will proceed. It's actually pretty standard language for a 504 eligibility meeting. Actually, they are not supposed to give you an indication one way or the other of the proposed outcomes, since that is, after all the topic for discussion at the meeting.
Just remember that you do not have to agree or disagree with anything right away.
