Then why does he use a nail-bomb? I'm thinking some weird plot between Lizzie Hexam and his dad, where his dad is trying to "retrieve" the sweet little boy that he based his books on by convincing Tom that it's all Really Really Real, and Lizzie is some secret ops type who has planted the evidence that Tom's past was faked, doped him with some time-release hypnotic so that he imagines the "Count" going all Nosferatuesque, etc. At least that's how it's playing out now, pending future plot twists and iterations on Maybe Magic, Maybe Mundane [warning: TVTropes].