Newsom did not invoke the 25th Amendment. He used it.
Trump said at a Nebraska rally that Iran could "take out" Los Angeles or San Diego and called it "a very small price to pay." The White House says he was speaking hypothetically — that U.S. cities would have been threatened if a nuclear Iran had not been stopped.
Newsom's move was the same one he always makes. He called Trump "mentally ill," posted "TIME FOR THE 25TH!," and told California's threat center to watch the state.
A governor cannot remove a president. The 25th only starts if the vice president and the Cabinet say he cannot serve. Newsom knows that. Trump is the fight. The amendment is just the latest round.