Skaters are not allowed to compete on the Senior and Junior Grand Prix in the same season (including pairs starting this season).
The current minimum age for the Senior Grand Prix is 14 as of July 1, 2012 so, technically, both Keiser (who already has competed on the JGP this season so is ineligible for the Senior GP) and Edmunds are old enough.
Even if there were a 3rd spot open, USFS is not going to give Skate America to a junior level skater such as Bell, Long or Edmunds (after all, they didn't give the 3rd SA spot to Gracie Gold last year before she was assigned to the final JGP ).
From her tweets, it sounds like Alexe Gilles has returned to Colorado Springs to train. Alexe's twin sister, Piper, was allowed to compete with Paul Poirier in Canadian qualifying competition/Nationals last season - she just wasn't allowed to compete internationally for Canada until this season.