Arguably, those cases are not applicable here because they deal with adjective defects in the appointment or designation process.
The situation with Obama is different because the Constitution says that he is not eligible to hold the office of President at all; doesn’t make any difference how he got there or what bases he touched or didn’t touch along the way.
He isn’t a de facto officer because part of the fact is missing. You could certify all day that he was a citizen; or born in the US; that is a part of the office and if he wasn’t a citizen or wasn’t born in the US, he isn’t the officer.
At this point, I have kind of gotten into ignorning these kinds of comments.
In fact, he was born in Kenya and is not eligible to hold the office. If it ever gets to a contested trial with competent counsel that is how it will come out. Bet on it.