This is a wrong approach. A macro doesn't separate paragraphs, but
belongs to them. IOW, you get the desired side-effect, but break
underlying syntax.

A better way to solve this would to add a function to
`fill-nobreak-predicate', like we already do for
`org-fill-line-break-nobreak-p' or
`org-fill-paragraph-with-timestamp-nobreak-p'.

I will add it to the "n" macro patch.