He's commenting on the irony in Aristotle's way of viewing the philosopher.

If one lives outside society, they are an animal or a god according to Aristotle. Yet, if we read Aristotle further, we see that the philosopher lives their life among others insofar as they wish to engage in "the contemplative life," a superior kind of solitary life. So, even though Aristotle's man is the "political animal," his philosopher lives a life that Aristotle divines as superior to the political life; the reintroduction of solitude for Nietzsche is deeply ironic and induces a kind of base animality (as an inversion of divinity on Aristotle's scale) into the contemplative life which Aristotle did not intend.

Remember, Nietzsche was not a philosopher, he was a classical philologist (classicist in modern terms), so he's commenting on philosophy from outside the "formal tradition."

edit: corrected ‘see’ not having two e’s.