AS TO TALON:
It did happen to him, Burning Bright I believe is the novel.... (Happened during Bug city).
All Summonings, no matter the source are voluntary agreements between the Spirit and the Summoner. The Spirit agrees to do the summoner a number specific tasks, and in return the Spirit gets <Unknown, not important. See the big red bar in the Core book in the magic section!>.
If the mage is dead, why would the Spirit stick around? It's not going to receive its reward for doing the tasks, you're dead!
If you paid the Spirit in Advance, and your dead, why would it continue?? It's not like you can ask for a refund
REMEMBER: Spirits are sapient, they have the full range of human emotion, intelligence and personality, they are NOT unthinking, mindless automatons.