A reader writes:

If Gabrielle Giffords is considered a Senate contender only because she was shot, Balko would have a point. But she was considered a contender for the Arizona Senate seat before she was shot. See, for example, this piece from Real Clear Politics, hailing her as the most fearsome Democrat in Arizona and a possible Senate contender. RCP considered her more likely to make a run for governor than senator, but she was certainly being talked about for the Senate.