One of the Dark Ones earlier questions was "Would you unleash balefire in my service?", and I tend to think that at this point, who is hit with balefire is less important than encouraging it to be used in a large and impersonal manner. IE: The Dark One doesn't care if the Lightsiders start using balefire to destroy His agents, as long as they start using it so much that they destabilize the Pattern and allow the Dark One to directly influence the Pattern. The Dark One probably didn't care when balefire was used on such a scale during The War of Power - it was the Aes Sedai and the Forsaken that realized reality was being affected and agreed to stop using it.

I think this may be where Rand's own words come back to bite him in the behind; he's taught the weave to another Ashaman and even if he no longer wants to use the weave, it's harder to control the actions of other people.