[bushpilot1]

Every Order, Resolution, or Vote to which the Concurrence of the Senate and House of Representatives may be necessary (except on a question of Adjournment) shall be presented to the President of the United States; and before the Same shall take Effect, shall be approved by him, or being disapproved by him, shall be repassed by two thirds of the Senate and House of Representatives, according to the Rules and Limitations prescribed in the Case of a Bill.

[Bubba Ho-Tep]

Did you miss the part about the supermajority that's required for an amendment? Since the vote is already a veto-proof majority, the president's signature isn't required.

Of course, if you're going to persist in this line of argument, you'll also have to argue that the Bill of Rights is also fraudulent, since they weren't signed by George Washington.