OK -- I wasn't looking at this clearly. In case there are others like me:
* the scope of *p is only global. My comment re: scope is just Wrong.
* there is never a call to someinitialization() *execpt* via the assert. If no assert() is called, the Bad Value prevails; if the assert() is called, it resets *p.
I feel a bit foolish, but found it easy to misread this at first glance. If anybody else didn't get it initially, hopefully this helps :P
I thought there was deeper magic, but it's really just programming flow, and knowing good practices re: assert() (or anything that has side effects).