> The null pointer satisfies all of the technical requirements of a heap-allocated zero-length array

This is not correct. You're allowed to do pointer arithmetic on malloc(0) if and only if it returns a non-null pointer. p+0 is valid for any non-NULL p, but NULL+0 has undefined behavior. This limitation of NULL pointers was lifted recently (ISO C2y), but historically it was UB; also, that change might have unexpected consequences, such as lower quality of static analysis, so I suggest not relying too much on it.

P.S.: Sorry for resurrecting this. I was researching the guarantees on argv[0] and read this incorrect statement by chance.