The 1790 law has changed a number of times and doesn’t resemble the original when Obama or McCann was born.
WOSG's point wasn't the current validity of the 1790 law, it was that the 1790 law provided a fairly accurate snapshot of the Founder's intent.
I submit that the 1790 law assumed that the off shore parent was a white male, and it was just to obvious for words to have to say so explicitly!