Basically, you can't prove that there is a connection between how Graendal died and how Asmodean died, especially since it seems no amount of balefire can remove a month or more from the Pattern. Rand used an incredible amount of saidin, more than anyone else could use unaided, and all he could manage was 15 minutes burned from the Pattern. Basically, Asmodean wouldn't come back even if Graendal was hit with balefire because he was killed too long ago.

And, even moreso, B.S. says nothing about the identity of Asmodean's killer.