They are almost certain that most people will never hear what Trump actually said. Almost no one goes to the source, especially not the people who think that the leftist media actually reports the news.
The fake news media's lies and half-truths are immortalized on the internet, ready to pop up with any internet search. Even if the lying leftist media formally retracts a lie, that news is buried on the internet after many entries which repeat the lie.
Timing is key as well. Outright lies are told by the media all the time. On the rare occasions they do retractions you find them days later on page 37A if you are lucky. The drivebys know all the tricks.