Note that searching the list archives does point to
http://nginx.org/patches/dtls/ and an indication that that experiment
was paused owing to a lack of a use case.
I suspect that if you want to report on how that patch works for you --
being aware that it was written for an older version of nginx, so possibly
will not apply as-is to the current version -- and/or describe your
specific use case, then there may be someone willing to update the patch.