My experience as an OT:
OT is almost never a "stand alone" service. Under IDEA occupational therapy is a "related service" that is provided in conjunction with other special education, based on the need identified by evaluation and determined by the team. I have sat in IEP meetings where the educational staff have argued that OT is not necessary because the handwriting is addressed through the regular classroom activities. It is really just a matter of how the school administration and faculty view both the student and OT, as well as how they interpret IDEA.
As for a 504 plan, that falls under the ADA, not IDEA. It requires that the school provide accommodations for a student with a disability. I have seen a student receive speech and social work services under a 504 plan, have it outlined that they need pencil grips, slant boards, special seating, etc, but NEVER seen a student receive direct OT services under a 504.
One caveat. No matter how hard you fight, if you get direct OT services for your child they (the services) will only be as good as the OT who is working in the school. You don't get to pick the OT (in most circumstances). Not all OT's are created equal. Hopefully the one at your school is really good with handwriting remediation. Many schools are reluctant to put OT on the IEP because they have not seen improvements when the kids at the school receive OT. That's the OT's fault.
Best of luck. I do hope he gets the services and help he needs.
