what should i do if my players asks if he can use occult speciality for sth if by just asking it eliminates an option?

i'm a beginner st that just started playing hunter 5e , and i wonder what should i do w occult rolls. i feel like if i tell my player that he can or cannot use a speciality on occult im letting him meta game his way out of mistery. lets say that my player has demonology asks if its sth demonic about some obscure book.if i say yes he knows that he should stick with looking for demononic clues. if i say no he knows that he at least doesnt have to look for anything demonic. i know that players should never meta game in rp but i feel like hunter is all about solving mystery puzzles and kinda informs them on a meta level,