The action would have been done as vice-president, not president. Vice-presidents are held accountable. This is why Trump got in trouble for defamation of E. Jean Carroll.

He defamed her as president and called it an official act. The case was put on indefinite hold. Then he said the same things while he wasn’t president. A new case was brought against him and he was found liable. Then, Carroll’s lawyer asked the original case to be resumed arguing that Trump’s statements couldn’t be an official act of the president since he performed the same action while he wasn’t president. The courts agreed and resumed the case and he was found liable again.