The initial cause of the two scenarios is irrelevant to the consequences of the outcome. If it's bad to abandon your family then it's equally bad to die on them. And it's completely rational to be afraid of an event that has bad consequences.

If you just want to say that your loved ones will survive, that life goes on without you, and you shouldn't be overly concerned about how the world will get on after you die, that's reasonable. But I completely and utterly disagree with going from that to "Fearing death is utterly irrational." Fearing death because of the negative consequences it will have on people you care about is completely rational.