My struggle with Klossowski's idiosyncratic reading of Nietzsche can be put down to the poverty of an education in philosophy within an Anglo-American philosophical culture. That meant reading continental philosophers on one's own. So there are huge gaps. This post at Spurious describes the problem:

"....we are too busy trying to educate ourselves – those of us who made the difficult transition in Continental philosophy after an undergraduate degree where we never heard the names Aquinas or Hegel, Scotus or Schelling, Kierkegaard or Nietzsche, Bachelard or Husserl, Heidegger or Adorno, Foucault or Deleuze, Sartre or Arendt and barely studied Plato or Aristotle."

Back to Klossowski.

In his Introduction to Nietzsche and the Vicious Circle Klossowski says that there are two hitherto points in reading Nietzsche that have been overlooked. Klossowsk says veiled, if not passed over in silence.

The first point is that as:

"...Nietzsche's thought unfolded, it abandoned the strictly realm in order to adopt if not simulate, the preliminary elements of a conspiracy. It therefore made our own era the object of a tacit accusation. It thereby made our era the object a tacit accusation....a Nietzschen conspiracy ...is not that of a class but that of an isolated individual (like Sade), who uses the means of this class not only against his own class, but also against the existing forms of the human species as a whole."

Klossowski's second point is that:

"...because Nietzsche's thought mediated on a lived experience to the point where it became inverted into a systematic premediation, prey to an interpretative delirium that seemed to diminish the 'responsibility of the individual', there is a tendency to grant it, as it were , 'extenuating circumstances' ...For what do we want to extenuate? The fact that his thought revolved around delirium as its axis."

I see it is a literary informed reading that pushes language to its limit or its own "outside." This outside of language is made up of affects and precepts that are not linguistic. So we have the world of delirium (the process of life?) that gestures to a silence when this delirium becomes a clinical state. It is a reading from within aesthetics and concerned with the movement of forces that produce emotion and sensation. It is one that places an emphasis on Dionysian energies

I've always read Nietzsche as working within, and reshaping the classic Stoic ethical tradition. This practical ethical tradition defined pity as a negative emotion, valued self-mastery and virtue, and was concerned to use philosophy to alleviate human suffering. In this tradition philosophy is a way of life.

With Klossowski we are working on the borderline of philosophy and literature. But back to Klossowski's interpretation.

Klossowski goes on to spell out what he means. He says that:

"... lucid thought, delirium and conspiracy form an indissoluble whole in Nietzsche---and indissolubility that would become the criterion for discerning what is of consequence or not. this does not mean that, since it involved delirium, Nietzsche's thought was 'pathological'; rather , because his thought was lucid to the extreme, it took on the appearance of a delirious interpretation--and also required the entire experimental initiative of the modern world."

So far so good.