Comment on the irony of the father's reflection that "That were awfully young, Wendy and Peter, for death thoughts."

To me, what is ironic about this thought on the part of
the father is that he is worried for the kids' sake when he ought to actually be worried
for his own sake.

When George thinks that the kids are too
young for death thoughts, he is worrying about how they will handle it.  Will this stuff
about death scare them?  He is not sure they are ready for
it.

But what he should really be worried about is his own
life.  Whether his kids are ready for it or not, the death thoughts they are having are
about him and his wife.  The death of some pretend zebras is not going to scare them --
they are planning for the actual death of their
parents.

That, to me, is ironic.