Naval officers (USN and USNR) separated between certain dates have all of their records archived at the NPRC in St. Louis. DOD has nothing to do with this. He was discharged from the Navy Reserves - those records weren't requested.
That's not completely clear. He didn't list his reserve service, but he did request the Report of Separation for "all years". The first is just for ID purposes, maybe. The second section is where the "what records" information is to be found, so perhaps he did release his report (or more likely reports, as why say "all years" if there is only one separation report?)