OK, technically, there is some tiny chance (i.e. small-weight branch) that you would survive, and conditional on this tiny chance (i.e. conditional on that we are considering your observations only in this small-weight branch), you would have observed it not decaying. But the weight of this branch is no larger than the weight of the branch where it didn’t decay if you did the experiment without the dying part.
You don’t observe that. You just die.
OK, technically, there is some tiny chance (i.e. small-weight branch) that you would survive, and conditional on this tiny chance (i.e. conditional on that we are considering your observations only in this small-weight branch), you would have observed it not decaying. But the weight of this branch is no larger than the weight of the branch where it didn’t decay if you did the experiment without the dying part.