It's not a matter of him being rushed into the limelight -- it's the truth that aside from some meaningless time last week, Kitna hasn't seen the field. Despite that, he looked sharp.
You can't blame Jon because he couldn't keep the team motivated in light of stunningly bad news of this sort. For one, he has NOTHING to do with the defense or special teams. For another, there are coaches who are responsible for team leadership as well. Finally, Jon cannot be a leader of this team -- it would totally undermine Carson Palmer to have the backup QB so involved. The other team leaders besides Palmer were the ones who failed to keep the team up if anybody failed. I would expect one of those guys to be Chad Johnson and another to be Rudi Johnson, knowing what I do about that team.
Did you watch the game? There was no reason to believe anything of the sort. Kitna played lights out until the news came about Palmer's ACL and MCL.
You need to take a look at those 2002 Bengals, as does anyone who believes that Kitna isn't a big improvement over Gus.