She's not.
Eligibility for in-ground burial at Arlington National Cemetery is the most stringent of all U.S. national cemeteries. However, most veterans who have at least one day of active service (other than for training) and an honorable discharge are eligible for above-ground inurnment.
https://www.arlingtoncemetery.mil/Funerals/Scheduling-a-Funeral/Establishing-Eligibility