Consider everything we now know Ialai knew about the wider cosmere, the efforts that Amaram was involved in, and the powers that Gavilar was meddling with... as the three people perhaps closest to Sadeas before he (or they) died, it seems reasonable to me that some of the implications yet-to-pass may be less about Adolin's role in Sadea's death, and more about the death itself and the knowledge (or access) lost with it. As I'm rereading SA in preparation for WaT, so many of his machinations come into a new light when viewed through this lens.