Sure, Nick ignored her advice. That night. But she doesn't know that he isn't going to follow through, and even more importantly, the audience doesn't know that he isn't going to follow through. All they know is he didn't throw Juliette out that night. Nick never once counters by telling Marie she's nuts, telling her where to go, telling her to put her advice where the sun doesn't shine or a thousand other things to make it plain he's not going to do what she tells him. Instead, he says nothing.
The best way to frustrate a cyberbully is to ignore him.