Wait, there's a limit on the number of abilities someone can have? *checks* Hmm, the templates all say "one or two"...
Eh, whatever, it's Decim's sheet anyway, and if he's decided to only give her X, Y, and not Z, that's that.
While the post doesn't specifically say it, although it implies it in a couple sections, those are templates for new Magical Girls, IE: those just starting out. As seen by:
Obviously a Magical Girl can pick up all sorts of new abilities over time, as is demonstrated by Nepgear's massive list, but she only starts out with one or two.