Simple, he was a trustworthy member of the forums, contributed a lot, was never rude and was just a generally a helpful and polite person.
Tony couldn't take care of the entire forums all on his lonesome (as awesome as he was at the job) so it was decided that another Super Mod was needed and because of Keaton's history in the forums, his time here, his contributions and his all round helpfulness, many people nominated him for the position. (Myself included)
With the support Keaton got and the proof of his actions on the forums, Angel and Devilmaycry saw it fit to make Keaton the new Super Mod, a position he deserves more than anyone else in these forums, you've got to do a lot of hard work if you even want to be considered, and even that was a special case, I doubt they'll be needing any new moderators soon.