Everything changes with a actual diagnosis.
I wouldn't assume the school would want you to be his aide. No harm in offering but I would just be open minded. There may be district/state rules about training requirements for that type of assistance, it may legally have to be a school employee rather than a volunteer. They may prefer to use an aide or nurse that can be responsible for assisting other children at the same time.
No need for mama bear yet, more need for a friendly and busy squirrel personality. Offer to your principal to assist in looking into it, offer to call the district nurse or whomever else they think might know how to proceed. Offer your time as they have so little.
Understand also the teacher/principal etc may have very normal personal gross out feelings to dirty diapers in a classroom. No need to apologize for that as it's not Bear's fault -- but it's a real gut reaction that may color their initial responses in a way they feel embarassed for later. Your school almost certainly wants to do whatever they are required to, but may need a bit of time to get used to the idea.
