“If the VP is not eligible for President, he is not eligible for VP.”
There is no Constitutional prohibition for a two term president from being Vice He could be President once more in the event of the death of the sitting President. The prohibition is against being ELECTED to a third term as President. In the event of his Presidents death, he would not be elected to the Presidency. He would assume office by Constitutional Succession. His election was to the vice Presidency. No Constitutional prohibition against his being elected VP.
Both the 12th and 22nd amendment are in force.
From the 12th: But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States.
Read the amendment.
He could not serve more than two years of another’s term.