Tomato, I think people are guessing it's him if he signed a written question to the Judge.
FWIW, here is the description of Juror #18 from the "observation" thread, for those who are interested;
18.The Artist-Bald, attractive, glasses, 50's-60's, large build, holds his notebook on a binder as if he's going to sketch. He looks around the gallery a lot. I thought we met eyes a couple of times, but who knows, that room is so huge!
This guy also had a very intense gaze. He took some notes. He rubbed his face and tapped his fingers to his lips a lot. He wasn't the only one doing stuff like that, but I'll get into that in my notes