You mean pulsars? They are assumed to be spinning, but maybe what we see as pulses is not the result of a spinning object. It seems to me that "neutronium" (what is the proper term btw?) is needed to explain the excessive spin rates. Just suppose there is nothing spinning that fast, doesn't it follow then that there are no neutron stars? Well, I must correct this, neutron stars are entities with specific characteristics, they are real. What could be different because of our assumptions is that they're not containing any collapsed matter. So what is eliminated then, is the need for an exotic form of matter.

Cheers.