Why do YOU think that there is a discussion of who shall be natural born citizens in the Naturalization Act of 1790?
In the 1790 Naturalization Act Congress conferred the status “citizen” on some and “natural born citizen” on others. My opinion of “why” this was done is immaterial: it does not change the irrefutable fact that Congress did it. In 1795 and thereafter the Naturalization Acts of Congress conferred the status “citizen” on some persons and never conferred the status “natural born citizen” on any persons.