alt Hacker Newsr is a single value per vector. You don't have to quantize it, you can keep it and quantize the billion+ other coordinates of the vector.
r is a single value per vector. You don't have to quantize it, you can keep it and quantize the billion+ other coordinates of the vector.
What they're saying is that the error for a vector increases with r, which is true.
Trivially, with r=0, the error is 0, regardless of how heavily the direction is quantized. Larger r means larger absolute error in the reconstructed vector.