Pointless speculation. Per the 12th Amendment, she could not have become the VP if she was not also eligible to be POTUS.
Her VP slot was not challenged but that doesn’t negate the issue or constitute a legal opinion on the Constitutional requirements to be POTUS or VPOTUS
But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States.
The Constitution lists only three qualifications for the Presidency — the President must be at least 35 years of age, be a natural born citizen, and must have lived in the United States for at least 14 years.
SHE HAS NEVER BEEN ELIGIBLE FOR EITHER
I agree that it will be treated as a moot point, but that does not mean that an ineligible candidate was not sworn in for VP.