What was debunked? “That” is not clear.
If what you say (it applies when a child is born outside of the US) is accurate, we still need to validate alien Obama’s “birth” place.
“That” means the idea that the law you mention applies to Osama’s birth, assuming, as we reasonably should, that he was born in Hawai’i.
Now, if he were hatched on Proxima Centauri, that’s different.