They haven't really been looking to limit his touches all that much. Since the beginning of the season, Mendenhall has typically taken 1 series per half off, has been spelled on a fair amount of 3rd downs (but also has played some of them), and has not been the between the 20's short yardage back (but has been the goal line back). There never was any limiting of any touches, as this has been the status quo since the first snap of week 1. The Steeler's have used Moore in roughly 60% of their 3rd down situations and Redman in a large majority of their short yardage, non goal line situations by design, not in any attempt to reduce Mendenhall's workload as the season progresses.
I would expect this trend to continue with or without Mewelde Moore, as the Steelers will probably use Redman to spell Mendenhall one series per half (they currently have been using Moore to do this). The main difference will be that Mendenhall will get slightly more 3rd down work, but it will not change his touch total nearly enough to warrent much of a difference in value (maybe 1-3 extra touches per game on average).
It is worth noting that Redman also suffered a concussion last week. If Redman AND Moore were to miss time, then you would probably be talking about a small value bump, as Mendenhall would probably be looking at anywhere between 5 and 10 more touches per game.
