Based on the latest view of the site, (seen below), I’ve determined that the letters that are missing can only spell out one thing.

“The Only Sensible Way To Live In This World Is Without Rules”
Wonder what’ll happen when all the letters are filled in…
It has to have something to do with Two-Face (possibly a photo!), since the original pumpkin carving is from “The Long Halloween,” and that storyline actually introduced Two-Face and how he came about.