The Bengals would have lost with or without Palmer. Luck wasn't a factor either, the Bengals were just completely outplayed on both sides of the ball. Their defense was awful, their playmakers on offense didn't show up, and that's why they lost, not because of 'luck' or an injury. Give me a break.
Also, that hit was definitely not on purpose, even Bengals Offensive Linemen (the people who were closest to Kimo and Carson when it happened) are saying that it was clearly an accident. You said it yourself, Kimo fell into him, he didn't hit him. Injuries are part of the game.
I bet the Bengals regret giving Carson that 10 year contract before the season even ended, good idea guys! They're going to be really kicking themselves if this injury affects Carson beyond this season. A lot of players are never the same after they get hurt.
Unfortunate? Yes, but it wasn't planned.
The Bengals aren't a very tough opponent anyway, what really worries me is next week's game in Indianapolis, the Steelers are going to have to be firing on all cylinders to win this one.