“I doubt his parents being us citizens would help because George’s parents had taken up permanent residence in Mexico.”
There is a formal proceedure for giving up your US citizenship and a record of it is kept by the State Department. Could you provide a link to the US law that takes away your citizenship if you live outside of the US for XX# of years without the citizen in question formally and and willfully giving up his(her) citizenship. I know of no such law and would like to know where you got that idea.
Absent giving up his citizenship at the US Consulate, George Romney’s father remained a US citizen and, per US laws, his offspring are born citizens. (Note: Not Natural Born) There was no need for George Romney to naturalize. He was a born US citizen.
Surely you see the difference between someone who left the county to settle permanently in Mexico to make a new life vs someone who knew it was only temporary and was in some type of service.