I 've had the same happening to me in a few instances, so for me the change does not really work either. In one instance the game even chose some random person who was not closest (Act 1, talking to pack leader Flint).
I wonder if in case of Flint and Auntie Ethel it has something to do with damage. Auntie seems to always pick the person who would have landed the killing blow, for Flint I am not sure. In my case Lae'zel was the first one doing damage to her - but that does not always seem to be the case. I had one run when the conversation didn't trigger for me at all.
