I think we have to stop babying QBs. They're a part of the team just like everyone else...and it's a hit and be hit game. QBs should not be stopped from doing what they do best (Armstong's case, running the ball) just because someone's afraid of injury. That isn't what football is about. It's a brutal game and if you choose to step out on that field in any position (even kickers) you have accepted that hitting, and the possibility of being injured, is there on every play. Hit and be hit, blocking and tackling.....that is the name of the game. No special exceptions from this rule just because someone is a QB or a kicker or whatever. To me it's all about old school - QBs will not slide, they will not run out of bounds.....I wouldn't ask Newby, Cross, or Janovich to slide or look to run out of bounds, so I certainly wouldn't expect Armstrong (or any other QB) to do that either.
Besides, ColoradoHusk makes an excellent point - a QB can just as easily, or maybe even easier, get injured standing in the pocket and getting creamed as a stationary target. At least when he runs he has a fighting chance to lower his shoulder and absorb the hit and even administer a little punishment to the would-be tackler.