Or, he may have used the term "fard" for the sake of simplicity and to stress it's importance, similarly to how sometimes "haram" is used instead of "makruh tahriman" when presenting a ruling to "common people" and there is fear that they may misunderstand it's gravity and say "oh, it's just makruh". Wajib or fard in terminology, the practical result is basically the same: it's obligatory to keep a beard which is at least a fistful long (at least according to the Hanafi Madhhab).