Under US law at the time, his mother had to reside in the US for a minimum of 5 years before Obama was born to be automatically a US citizen. She was 19 at his birth.
As your your question, It could be argued that all Obama’s laws, decrees and EOs as well as the regulations passed by his appointees could be found to be unconstitutional and voided if he were determined to be ineligible to be president.
No, she was 18.
Actually, if little Barry was born outside the United States to Stanley Ann and Barry Senior, the rule at the time was that Stanly Ann, the citizen mother, had to reside in the U.S. for ten years prior to the birth, and five of those years had to be after reaching the age of 14. That would mean she had to be 19 at his birth to confer Natural Born Citizenship on little Barry. Problem was, she was only 18 at the time of his birth.
Stanley Ann was born 11/29/42. Little Barry was born 8/4/61, almost four full months before Stanley Ann's 19th birthday. That's why everyone was keying on Kenya, and why Hawaii became so important to the whole thing. If there was no doubt he was born in Hawaii, there was no issue. His stating in his past that he was born in Kenya, and all the smoke and mirrors around his real birthplace and the birth certificate is what drives the NBC issue with Obama.
I believe that those laws would stand unless overturned for some other reason. Believe we had a couple of ineligible Presidents in the 19th century and those laws where upheld