Obama's eligibility was not challenged until after the election. The time to challenge would have been before. You can't sit back and do nothing to stop a State from putting him on the ballot, and then complain later when he wins.
Nonsense. The president is elected by the Electoral College. Akeny v. Governor, for example, raised that challenge before the Electoral college's vote. It was therefore timely, and more to the point, specifically addressed the points raised by the complainants.
They lost, fair and square.