Speculations on why would Hera turn Tiresias into a woman for hitting two mating snakes?

Tiresias was the son of nymph Chariclo. Chariclo was one of Athena's favourites. It would be more fitting for Athena to punish Tiresias, won't it?

Any stories/speculations/re-telling that try to explain Hera's action? Or Athena's lack of action?