[css-exclusions] whence margins?

The exclusions spec has this:
> Exclusion area
> 
> The area used for excluding inline flow content around an exclusion box. The exclusion area is equivalent to the border box for an exclusion box.
> 


Shouldn't that be 'margin-box' instead of 'border-box'? Otherwise, it sounds like the margin of the exclusion won't actually have any effect on the inline flow, and authors will have to resort to using ::before and ::after to add to the wrapping context, to keep the text from touching the border of the exclusion.