Obama's Job Approval 16% Among Birthers

[True Federalist (진정한 연방 주의자)]

Such as, they think it means - or  even can be interpreted to mean - "born in the USA". It doesn't. It's a clear-as-daylight phrase that means "is a citizen by birthright", ie the opposite of a naturalized citizen.

That assumes that a person cannot be granted naturalized citizenship at birth.  A hyper-picky reading of the XIVth Amendment could be interpreted in a manner that would deny native-born citizenship to a child born abroad of American citizens.  I don't think the debates held in Congress when they sent the XIVth to the states would back that interpretation.  If anything, considering that the debates indicated that those born in the territory of the United States to foreign nationals who had not undertaken steps to place themselves under the jurisdiction of the United States were not to be included in the automatic citizenship grant, reciprocity would require that the children of American citizens are natural born citizens, no matter where the birth takes place.

Aside:
I wonder how many birthers hold the logically inconsistent position that the children of illegal immigrants need not be granted citizenship under the XIVth?  (A position I agree with, but one that logically undercuts the birther argument, that if Barry was born Kenya he would be ineligible to the Presidency.)

[True Federalist (진정한 연방 주의자)]

Whether Americans born abroad have natural-born citizenship or naturalized citizenship granted at birth is a present an obscure constitutional question not particularly subject to.

... one wonders why they felt the need to point out that naturalized citizens are citizens - maybe just clarifying that one state's naturalizations are valid in every other state as well?

No.  Naturalization was already a Section 8 power of Congress, and worded so that States didn't get involved in the process.  Rather the mention of naturalized citizens is a reaction to the Dred Scott decision which held that State citizenship and United States citizenship need not be equivalent. They are included so as to make it clear that for a resident of a State, one cannot hold only one of those citizenships.