OK, so Granny Sun's death could possibly have been stopped by a higher power such as FAST SABRE Qi Liu.
What about Zhang Cuishan's death, Xiao Feng's death, etc. Surely they couldn't have been so fast that nobody could have intervened. I understand that Jin Yong needed them to die. But FTFOI, can you think of anyone who could have stopped their death?
Well, if we're to stick to the original situation, someone could seal their pressure points before they commit suicide.