I found my own answer by goggling it, and it explains why both Jackson and Naomi Watts were at a party for the movie even though neither was in it:
Naomi Watts Talks About Meeting Fay Wray: “Meeting Fay was wonderful. We had a fantastic night in New York. A gentleman by the name of Rick McKay hosted a small dinner and Peter clearly had been in love with this woman since he was about nine years old, that was his first crush. He talked with her and told her that he was doing this film and how much it meant to him, and how it drove him to being a filmmaker. She was very attentive.
I think he was very moved by the experience of actually being in the same room as her. In fact, I think I saw a tear well up. It was a lovely moment. And then he introduced me as being the new Ann Darrow and she looked up at me and went, ‘You're not Ann Darrow, I am! [laughs] I'm Ann Darrow!’ And I thought, ‘Oh great! She's 96, and her humor is still right there.’ And then I had a moment of like, ‘Oh God, what if she doesn't like me? What if she thinks I'm not good enough?’ And all that typical stuff.”
Naomi Watts on Getting Fay Wray’s Blessing: “We had a nice dinner and chit-chatted. At the end of the night, we dropped her home to her house and she got out of the car. We all kissed and hugged, and she whispered in my ear, ‘Ann Darrow's in good hands.’ And that was a special [connection.] That was some great passing words because it felt like she was giving me permission, and I was given the baton, you know? I was hoping that that night was going to be the first of more, which it was for Peter and Fran. But sadly she passed away a few months later and I wasn't in the country to meet her again, in between that time and her death. But, you know, you didn't want to overwhelm her with too many questions.”