Ok, I've been wondering about this question for many years and I don't know whether I just don't understand the basic concepts enough. If you have a rapidly-spinning neutron star that continues to collapse down to a singularity, what happens to the conservation of angular momentum from the spin? As the circumference of the neutron star approaches zero, what happens to the speed of the spin? Would it actually have to approach c? Would the energy get bled off into some other form?