I'm not sure why a package is not available, but if you look at the Makefile you'll see:
Code:
> cat /usr/ports/editors/emacs-nox11/Makefile
...
WITHOUT_X11= yes
PKGNAMESUFFIX= -nox11
MASTERDIR= ${.CURDIR}/../emacs
.include "${MASTERDIR}/Makefile"
It's really building the emacs port and using WITHOUT_X11. Which FBSD version are you looking for a package for?