And all this time I thought it was to make Bards feel useful
j/k
There are many discussions about the Puppy Charm and I believe its been proven that the Charm itself is Timed. So it does not matter if its a Bard or Barbarian doing it.
However, I've been seeing Stone duty getting assigned to "faster" characters, those with speed boosts or natural speed enhancements (you know the ones that your always seeing the back of their heads when questing). As not only are the Charms Timed, so is the appearance of Beholders.
That is interesting that Augment Summoning does effect the Charm, that would be even more buffage.