Nietzsche's suggestion that aesthetics should be the supreme value above truth, as opposed to truth as the supreme value above aesthetics, is what lead to the catastrophe of modern aesthetics whose quality isn't beholden to truth, there is no such thing as "true beauty" anymore, it's just a matter of who most represents the "spirit of the age" (or the "current year", as it manifests politically).
Nietzsche's idea of truth here is contaminated, and it is the contaminated conception of truth that he rebels against. After truth passed from subject (revelation, truth reveals itself consciously) to object (freethinking, the Enlightenment, truth is an object to denude), materialism rebels against the incoherent, freethinking enterprise, and identifies truth strictly with empiricism: what we see and hear, and ends up raising utility above it (and Nietzsche is actually rebelling against utility as the supreme value more than he is against truth). Nietzsche is working with the materialist conception of truth, and of course realizes that the empirical is altogether a matter of perspective, if what we see and hear is synonymous with truth, then there is no monolithic truth, each person has his own "truth". But in order to accept this conclusion, one must first accept the entire post-freethinking enterprise, the materialist, realist enterprise. Once truth becomes purely relative, then it ceases to have any significance beyond taste, and if truth is merely a matter of taste, then taste itself is the predicate upon which it dependent, and taste itself is aesthetics, so Nietzsche says truth as a product of taste is of no value compared to the taste itself, merely a servant of taste. And once this is accepted, then the taste which is the most exotic will always be most valued, whatever is the "spirit of the age", the "current year", is what is most fresh, and therefore most exciting, and this impulse assumes control over all art and politics. But of course the dialectic is not complete, to be complete in abandonment of God, the vagaries must be abolished, and destruction becomes the measure of all things, because destruction is the ultimate excitement, the ultimate in freshness, as it is always the ultimate rebellion against every creative act prior to itself.
Anyone interested in reading about this in depth, Father Seraphim Rose wrote a work on it (you can skip the preface, which just explains it's a chapter of an uncompleted book): oodegr.co