If I can read the ebuild right, americas army requires (on x86) x11 for running. That is a bad thing(tm) on a x86 based x11less server with use flag 'dedicated' set, isn't it?
Have you tried to install it without x11?
Yes, I _have_ it installed on my x11less server. And I was very surprised that "emerge -Duvat world" was about to install all the x11 stuff for no visible reason!
Fixed in CVS (no bump)