The Franco character, although originated by and named after James Franco, was property of GH. They had RH take over the role after learning he could no longer play Todd Manning. Even though GH redeemed Franco by curing him of the brain tumor that caused his mass-murderous ways, they no longer wanted the association with James Franco. As I understand it, James Franco was accused of sexual misconduct by a student at a university where he was a guest professor. The ensuring scandal was enough for GH to want to disassociate the Franco name and the character's subsequent portrayer from the show. This was never formally announced or confirmed by GH or ABC, but was much-speculated as the reason for the Franco character's death.