I'm not a legal type. Can you sight the provision that says if the president was fraudulently elected to the office then his vice president would become president.
Of course not.
Biden is not the Vice President of Barack Obama.
He is the Vice President of the United States, an independent and separate Constitutional office. He was elected to that position legally, in accord with Article II and Amendment XII, and in the case of a vacancy in the Office of President, FOR ANY REASON AND OF WHATEVER CAUSE, Biden becomes President.
It would be interesting to know the answer to that. One would think that if obama is declared illegitimate, all of his appointments and executive orders would be illegitimate as well.