Well, if anything else, this convo shows that rebels had no intentions to shoot at civilian aircraft, nor did they expect one to fly over there in first place. That's of course assuming that this leaked record is authentic, which we cannot really know for sure at this point.
Was the plane supposed to fly over this area anyway? It seems like a terrible choice on the part of the Malaysia Airlines.
It seems that Kiev advised all companies to avoid that area but they didn't bother to close the airspace.