1) He is telling her to be quiet and this will be okay for her. In this scenario, he knew for a fact she was using Mara Lago as a hunting ground and doesn't want that info to get out. Trump's supporters think that b/c he wasn't a child molester himself he's safe here. Remember, no one accused Joe Paterno of being a child molester either.
2) She was previously nice to him, and he's such a sociopath that he cares more about that than the fact she is a serial child abuser. This is how he views the world. Everyone who likes him is great (even when they are despicable), everybody that doesn't is horrible (see John Lewis).