I have always believed the Von Oelhoffen hit was dirty. The reason is that in the previous Cinci Pitt matchup, a devastating home loss for the Steelers which gave the division to Cinci, currently suspended MLB Odell Thurman hit Ben low, late and dirty and forced him to miss a few games with a knee problem. Pittsburgh has a long history of dirty hits on Qbs under Cowher, with Greg LLoyd a principle culprit. Also remember the low hit on brady in the 2001 AFCCG. I feel strongly, knowing the way Pittsburgh historically played under Cowher, the bada$$ culture in that locker room, the Pittsburgh culture established by Lambert et.al. of nasty dirty defensive football, and the late hit by Thurman, that hitting Palmer low as retaliation was in the minds of many Pittsburgh players, an example of eye for eye on-field justice Steeler style.
Cowher probably only had to show a video of the Thurman hit to his team a few times, say nothing, and sit down for the message to get out and plausible deniability to rule the day. I also feel that people who believe that hit was an accident are very naive. it was no accident that the Competition committee changed the "roughing the QB" rules that offseason, in part to put a halt to an escalating Hatfield McCoy vendetta between those teams.