I think you're being a little bit unfair. The same block then continues:

  This is called an integer overflow. At best, we might just get an error. At worst, our computer might compute the correct answer but then just throw out the 9th bit, giving us zero (0000 0000) instead of 257 (1 0000 0000)! (Python actually notices that the result won't fit and automatically allocates more bits to store the larger number.)

The article is introducing the concept of integer overflow.