Habster’s take:

Before training camp started, I was very confident that Sergei Kostitsyn would turn heads and make a good impression with his versatility, hard work and overall skill set. Coach Carbonneau has been impressed enough to consider keeping the younger Kostitsyn for the final week of training camp.
Carbonneau purposely placed Sergei with a checking line (Milroy and Chipchura) to see if he could adapt to a defensive role. Obviously, the coach liked what he saw, especially being impressed with his determination and versatility which is something I’ve been mentioning in past articles/comments about his play (see Sergei Kostitsyn ).
Realistically, the odds of Sergei Kostitsyn making the Canadiens are low but if he does get an invitation to Mont Tremblay and continues to impress the coaching staff, we won’t have to wait long before he get his chance especially if there are injuries during the season.