It's not that he likes vampires — he "doesn't know any, personally," — but he does try to keep up with the "silly stuff" that the grandkids are into. Famous Mormons unite!
oh mitt.... come on.... i use that old excuse myself. "oh, yes... i am reading this YA teen romance right now, because uhm, uh, I like to connect over it with my nieces. yes! it uh, makes us closer and such" its okay to love some YA books, they're fantastic these days (actually, mostly excepting twilight)
also, considering the fact that the twilight books are full of nuggets of thinly veiled mormon beliefs and values, this is incredibly unsurprising.