Pretty sure there isn't any precedent for citings being lengthened because of injury. However, Tuilagi punching Ashton at the end of last season does shed some light on the judges powers.
Since the end of the season is near we sought evidence about the Player’s plans for playing during the next 5 weeks. We were informed that he is due to play for the England U20 7’s team over the next weekend, the Aviva Premiership final on 28 May (or England v Barbarians on 29 May if not selected for Leicester) and for England Saxons in the Churchill Cup on 4, 11 and 18 June. We are therefore satisfied that the suspension may be served without any break as he will miss five meaningful matches. For so young a player this is significant, particularly as this would have provided him with the opportunity to stake a claim for the England RWC11 squad – an opportunity which he might now miss.
So while he didn't get his sentence suspended, it would appear that the judge can suspend a sentence if he doesn't feel it would have significant impact. However, unless the RFU had a indepedent doctor checking when Chris was fit every week or so how would they know if he was fit or not. The club internally suspended him for 6 weeks(?) while he was injured (so we assume), so hopefully that will be taken into account and he'll be free to play, assuming the club have a decent legal team. So he'll probably get a hefty ban!