  The AdS/CFT dual description of a peripheral heavy ion collision involves an
asymptotically AdS rotating black hole. The explicitly known black holes of
this kind, with planar event horizon topology [the "KMV$_0$" spacetimes], have
been shown to be unstable when string-theoretic effects are taken into account.
It has been argued that this implies a "holographic" angular momentum cutoff
for peripheral collisions at very high energies. However, the KMV$_0$ black
hole corresponds to a specific velocity distribution in the aftermath of a
peripheral collision, and this distribution is not realistic at all points of
the interaction zone. It could therefore be argued that the angular momentum
cutoff is an artefact of this particular choice of bulk geometry. We
demonstrate that, on the contrary, a Quark-Gluon Plasma with any physically
reasonable internal velocity distribution corresponds to a black hole which is
still unstable, in the same way as the KMV$_0$ spacetime. The angular momentum
cutoff is therefore a universal prediction of the holographic description of
these collisions.
