I agree with you. This is not unusual. The various factions within the GOP tend, first, to support their winners of primaries; and, second, other candidates that are acceptable to them who have the best chance of winning. Rove was in he second category with regard to Akin prior to the gaffe. Now that Rove has withdrawn support for Akin, it is imperative for Akin’s faction of the Republican Party to belly up to the bar. The way Rove sees it, less money for Akin means more money for George Allen or for Josh Mandel.
I believe that you are right, that is the way Rove and others at the national GOP level see it. Traditionally, that's the way it has worked. The party has very limited funds compared to candidates, PACs, etc. So they husband their money and steer it to those with the best chance of a win. It doesn't make much sense to spend money on candidates that are likely to lose. In Akin's case, its more than likely, his race is no longer competitive.
Except that Rove had promised $15 million to the Missouri Senatorial campaign, then withdrew it when Akin refused to resign saying he can't win.
Well now we know that he can win and has a better chance than either Allen or Mandel. So we know that the reason that he gave for withholding the funding is a big fat lie.