>> “ why DID they use the word “citizen” instead of grandfathering in those who had been natural born subjects?” <<
.
What a convoluted question.
They used the word citizen because they became citizens when the country came into existence, and thus could not be “natural born” citizens if they were created citizens.
Damn you’re stupid (and astoundingly mendacious).
Were they citizens by birth, or by naturalization?
And why did they not grandfather those who had been NBS, and only them, if that was their goal?