I have two issues with this sentence:

Values other than stretch cause non-replaced absolutely-positioned boxes to use fit-content sizing for calculating auto inline sizes.

In the "Other details" part of the rules for justify-self on absolutely-positioned boxes.

• It should be clear that normal acting like stretch is not a value other than stretch
• the size in question is not an inline-size when the absolutely-positioned box is orthogonal to its containing block

Both of these issues apply equally to the equivalent sentence:

Values other than stretch cause non-replaced absolutely-positioned boxes to use shrink-to-fit sizing for calculating auto block sizes.

in the rules for align-self on absolutely-positioned boxes.