Great find! I wonder why they are sure this one is Epicurus:
I'm going off on a limb but the hair is essentially identical, the major difference is that the bust does not depict Epicurus in his typical serious and stern expression. Other details seem to match too; from the length of the classical beard to his rectangular face and nose. It's interesting since I've never seen it before and its missing from Frischer's book about the various statues and sculptures tied to the school.