http://www.mha.nic.in/pdfs/oci-chart.pdf
OCI status as per the Ministry of Home Affairs.
I too know of people who have OCI cards who have previously held DGCA licenses.
Technically if you have OCI I assume you also have Dual nationality status, then you should be having a Indian Passport and you need to use that to get your license, thats what others I know did.
The interpretation at
DGCA is correct YOU DO NEED TO HAVE AN INDIAN PASSPORT to be issued a Indian CPL/ATPL or else get a FATA License.
If you have an OCI card and your country allows DUAL nationality apply for a Indian passport; if you already dont have one and then reapply at DGCA.
OR ELSE refer to the post above!!!
Coz it sure does happen in incredible India.