Cousin found unopened LEGO Black Knight's Castle (6086) (released 1992), gifted it to son

As the title says, cousin found his old unopened LEGO Black Knight's Castle (6086) - complete even with an old LEGO bag - and gifted it to my son, thinking he would like it. Cousin received it sometime in 1992 when he was just a small boy. The box is in great condition and sealed too. While I have never gotten into medieval sets, this shocked me as it has these amazing see-through windows, is a pretty sizeable set and has ghosts and horses. We obviously cannot accept this as a gift knowing...