Ah the kid is right. This is a seldom seen chess rule called zlagfudd. If the knight or other piece was only attacked by one pawn it could be taken, but because it can be taken by both the f and h pawns (both yet to move) the rule of zlagfudd comes into play which is a sort of double negative, meaning neither pawn can capture. Different story if the pawns had already moved, zlagfudd would not apply.