I’m not sure I buy into that summary.
Deckard was probably one of the special ones as well, no mandated expiration date, like his new girlfriend at the end of the movie.
If he and his GF were special, it may be that they will age naturally as well.
Disclaimer: I never read the book.
I did. The plot was pretty cut-and-dry: Deckard goes out and kills him some replicants, while adhering to some new, post-nuclear-war religion. There wasn't the anti-slavery moral tale woven into the plot, like there was in the movie.