Ben Thomas: It is within my power to drastically change his cirumstances, but I don't want to give that man a gift he doesn't deserve.
The only ways Tim/Ben could have died are by heart failure and/or respiratory paralysis. Both of which mean that the toxins reached the heart. If they hadn't, then he would only have had a paralyzed right arm and been in extreme pain. The logic of this movie implies that either his heart was unaffected by the toxins and he still somehow died or his heart was affected by the toxins and they decided to transplant it anyways.