BTW, things work correctly when the objects live inside a real array:

  #include <stdio.h>

  int main(void) {
    int arr[16];
    int *p = &arr[0] + 1;
    int *q = &arr[1];
    printf("pointers: %p %p %d\n", p, q, p == q);
    return 0;
  }

The result is perfectly correct and predictable, as the Standard guarantees pointer comparisons in this case:

  pointers: 0x71b35ac790d4 0x71b35ac790d4 1

The original code in the article relies on UB, I think, so all bets are off.