A few points can be made with regard to this ebuild:
1) Relnev (Steven Fuller) no longer maintains the port, so it should probably be called quake2-i.o or quake2-bburns (Brendan Burns is the maintainer as of March 2002....) or something similar.
2) In the ebuild itself, there is a description: "The Icculus linux port of ID's quake2 engine"; icculus (Ryan Gordon) is a person, he didn't do this. icculus.org is the website so it should be "The icculus.org linux port of ID's quake2 engine"
3) (And this is probably the most important bit), the xatrix and rogue mods /do/ build when you do it properly, as in, downloading the seperate source for each. So they should either be seperate ebuilds, though they still require the quake2-i.o base, or should be compiled anyway (after fetching the appropriate files) and then have seperate quake2-xatrix-data/quake2-rogue-data ebuilds for people who actually want to play them.