Although I think it's funny that 10+ games per year are seemingly picked at random to have the "Game of The Year" title bestowed upon them, I am kind of glad to see this version of Halo 4 come out. This can't do much of anything other than increase the population a bit, so since this can't hurt, this is is A-Okay with me! Even if it gives the population a 5k player population increase, I'll be satisfied since I don't really expect much more than that.
They usually base the eligibility of a game of the year candidate by sales figures, or awards. If a no name magazine like "Penguin Fart Monthly" gave Halo 4 their game of the year award, then that's enough to count. Even so though, Halo 4 did sell pretty well with 8.46 million units sold as of August 10th (that's according to VGChartz.com). So either of those two reasons are why Halo 4's getting a game of the year edition.