On Sat, 1 Aug 2015 17:35:38 -0600

Hello Idris,

I would think that your only hope in this case would be through the use
of \startparagraph \stopparagraph, for otherwise TeX does not know
where a paragraph is to end (only where one begins, through an explicit
\par or through an implicit blank line).

My guess, untested, would be \setupparagraph[after=\thinrule]