And considering how many people immediately bought it - apparently because they can't differ between "being responsible" for someone's death and "having actually directly killed" someone - it seems to work.

If one agrees that Graendal didn't directly kill Aran'gar (but that Rand did this) or destroyed Mesaana (Egwene did that), the same could of course apply to Asmo's death to explain Graendal's responsibility: Ultimately Asmo's death caused by Graendal but not directly doing the actualy deed itself; Slayer did it.