why was gulliver struck with inexpressible delight upon hearing the account strulbrugs ?

Gulliver was delighted by the thought of immortality.

I freely own myself to have been struck with inexpressible delight, upon hearing this account: and the person who gave it me happening to understand the Balnibarbian language, which I spoke very well, I could not forbear breaking out into expressions, perhaps a little too extravagant. I cried out, as in a rapture, "Happy nation, where every child hath at least a chance for being immortal!