Granted, we haven't heard every detail of this conversation, but everything I've seen so far in the moments leading up to the crash, they were talking about events on that plane. The comment about the ice build up seems relevant to me. I can understand either point of view on the rest of the comments about their experience, but to me, it seems relevant to the flight.
I guess it all comes down to whether or not they could've done things in advance to avoid that stick shaker stall warning. The big thing that sticks out more than anything is that these two had no clue what to do in the icing conditions. With or without the conversation, that doesn't change.
Yes, I can understand the potential problems of random conversations in the cockpit, but here, this whole issue seems like it is trying to distract us from the fact that not enough is being done to train certain pilots.