I have to disagree with you here - Alioto is lying. It's on the very first line where the Constitution starts describing the Supreme Court.
Article 3, Section 1 first line:
The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish
The court itself was established through an act of Congress, the Judiciary Act of 1789, and Congress has had the power to both set the number of judges and impeach them throughout the entire history of the United States. If Congress had the will to do so, they could repeal and replace the Judiciary Act and still be under their Constitutional mandate - and the Act has been amended and expanded on substantially by Congress since its inception.
Alioto should be disbarred for even suggesting such a facetious legal theory.