LIB_DEPENDS not respecting packages-specs(7)?

[Jacob Meuser <jakemsr_(_at_)_jakemsr_(_dot_)_com>]

I'm trying to make sure SDL is not of the no_x11 FLAVOR.

puff:/usr/ports/mystuff/multimedia/mjpegtools% grep sdl Makefile
LIB_DEPENDS=            SDL.2:sdl-1.2.6p0-sun-!no_x11:devel/sdl \
puff:/usr/ports/mystuff/multimedia/mjpegtools% pkg_info | grep sdl
sdl-1.2.6p0-sun-no_x11 cross-platform multimedia library
puff:/usr/ports/mystuff/multimedia/mjpegtools% make clean depends
===>  Cleaning for mjpegtools-1.6.2
===>  mjpegtools-1.6.2 depends on: SDL.2 - found
===>  mjpegtools-1.6.2 depends on: gdk.1.2,gtk.1.2 - found
===>  mjpegtools-1.6.2 depends on: jpeg.62 - found
===>  mjpegtools-1.6.2 depends on: png.4 - found
===>  mjpegtools-1.6.2 depends on: pkgconfig-0.15.0 - found
===>  mjpegtools-1.6.2 depends on: pkgconfig-0.15.0 - found
puff:/usr/ports/mystuff/multimedia/mjpegtools% 

I tried other variations, such as
LIB_DEPENDS=            SDL.2:sdl-1.2.6p0-*-!no_x11:devel/sdl \
LIB_DEPENDS=            SDL.2:sdl-1.2.6p0-*-\!no_x11:devel/sdl \
LIB_DEPENDS=            SDL.2:sdl-1.2.6p0-!no_x11:devel/sdl \
LIB_DEPENDS=            SDL.2:sdl-1.2.6p0-\!no_x11:devel/sdl \
LIB_DEPENDS=            SDL.2:sdl-*-!no_x11:devel/sdl \
LIB_DEPENDS=            SDL.2:sdl-*-\!no_x11:devel/sdl \
and
LIB_DEPENDS=            SDL.2:sdl-!no_x11:devel/sdl \

All behave the same.  Am I just being dumb (if so, please shed some
light), or is the documentation not really reflecting the
implementation?

-- 
<jakemsr_(_at_)_jakemsr_(_dot_)_com>