[edge919]

It was the basis of the denial. You even posted a link to it.

Because petitioner has failed to show a clear legal right to the relief requested, he is not entitled to mandamus relief.

[Nero Germanicus]

That is not a ruling on standing.
The issue before the Florida Supreme Court was should the plaintiffs be granted a Writ of Mandamus to compel the lower Florida Appeals Court to reconsider the plaintiffs’ claim that Obama is ineligible due to his not being a natural born citizen.
The Supreme Court denied the Writ of Mandamus on the grounds that the plaintiffs were not legally entitled to the Writ.
The Supreme Court did not deny the Writ of Mandamus because the plaintiffs lacked standing to bring the lawsuit.