Well, the feat has a prerequisite of one or more natural weapon.
A human monk doesn't have any.
His unarmed strike is considered a natural weapon for the purpose of certain spells and effects, but it isn't actually a natural weapon.
Oddly, if a minotaur monk, for example (who has the prerequisite) took the feat, the 'considered a natural weapon' clause would probably let him apply it to his unarmed strike.
But the human monk doesn't qualify for the feat, so he can't exploit the same weirdness.
-Hyp.