Rukelion wanted to do so much worse to Juliet than sue her but he was truly afraid of what he would do if he saw her again knowing now that she was not only the reason he had been separated from his wife but that she couldn't remember him. He didn't want Daisy's efforts of looking into lawyers for him to go to waste though.
She had done that while he was at school when she could be doing better things because she wanted justice for him. That meant a lot.
He decided the safest course of action was to try and avoid taking this to court. Threatening Juliet had always worked for him in the past. If she wasn't willing to give him what he wanted no questions asked then he would sue her.
As Daisy said, he did have a strong case with how much hassle this had given him. There were so many fans of that stupid novel or the actor who played him in the movie that had stopped him and asked if he was trying to look like Rukelion Blaze on purpose.