“Mr. Trump has falsely asserted“
That’s President Trump scumbag and the assertion is plausible.
Referring to the President of the United States alternatively as "Mr." is a perfectly acceptable journalistic practice. Has been since the early days of the Republic. The custom is that, after the first mention of the President in the article where he is referred to as President __________, after that "Mr." can be used. This is considered a respectful form of address, as anybody else can simply be referred to by their last names alone.