The 1790 act conferred a legal status upon a person who without this act would be an alien.
The foreign born child of a citizen was not in 1790, is not now, nor ever has been a natural born citizen in fact. From 1790 through 1795 they have, in law, been considered as natural born citizens. They were not in fact natural born citizens.
The foreign born child of a citizen is an alien requiring naturalization.
The only power Congress has on this head is naturalization. The foreign born child of citizens, Bellei, lost his citizenship because he did not fulfill the terms of naturalization statute. Congress can only strip citizenship from those to whom it grants citizenship.
The foreign born child of citizens, Bellei, was an alien who without Congressional act would be an alien. This has always been the case.
Since 1795 the status conferred has been “citizen”. The act in force at the time of birth controls.
Your argument is the Constitution gives Congress the power of naturalization which is true. But the Constitution distinguishes between a “naturalized” citizen (Art I, Sec 8, Cl 4) and a “natural born citizen” (NBC) (Art II, Sec I, Cl 5). A “naturalized citizen” is not the same thing as an NBC. By definition an NBC doesn’t have to be “naturalized” as a citizen because he is automatically a citizen upon birth.
So there’s some vagueness and ambiguity in the Constitution about this. Obviously Congress cannot “naturalize” an NBC. However, since the Constitution does not define NBC, Congress and/or the courts need to.
Nevertheless, Congress HAS legislated that an NBC MAY be in some cases born on foreign soil. Congress has NEVER legislated that an NBC may NOT be born on foreign soil. And for the above reasons, the naturalization statute in Bellei may not apply when the issue is NBC.
That still reasonably leaves open the issue whether an NBC may be born on foreign soil. And again, IMO, either Congress needs to expressly clarify whether an NBC may be born on foreign soil and/or the courts need to tackle individual NBC cases of this sort.