KC is absolutely correct.
There was no need for GOPB to be "naturalized". He was born an American citizen.
The source of the confusion might be the paperwork involved in registering the foreign birth of an American citizen. It is incumbent on the parents to notify the American Embassy or a Consulate of the birth. The Embassy or Consulate then issues a registration of the birth, stating that the child is an American citizen and subject to all the benefits thereof.
I have heard people born in this circumstance refer to these documents as their "naturalization papers", but that's not what they are. They are his "citizenship papers".
I went and found the certificate and it does say ‘Citizenship’ instead of ‘Naturalization’.
Reading into the document is interesting though and I am going to try to post a picture do you can see it but it says;
‘... is now a US citizen...’ which I contend it would not if I was previously a US citizen.
I am unable at this time to get FR to let me paste some lines or a picture. I will try to get that figured out.