It just seems counter intuitive to create a show about the character of Clarice following the events of Silence of the Lambs, a show which is directly referencing and even showing some of the events of that film/book, but the show is not allowed to reference Hannibal.
I'm not saying Hannibal needs to be featured on the show, nor does he need to appear at all or even be a focal point. I know this boils down to a stupid issue with the rights, but it's just strange. In SOTL, Clarice's main task was to get inside the mind of a serial killer (Hannibal) in order to catch another killer. Hannibal develops a fixation with Clarice, forces her to confront her childhood, and also escapes custody.
As someone else said, it will just be a weird "elephant in the room" thing, I guess.