Title should have (1986), the year this was published.
Part of the set-dressing of Brave New World (1932) is that people go fairly speedily from retirement to soma overdose to being recycled.
(it doesn't affect the plot of the book, nor is it particularly relevant here, I just mention it to note that "death on schedule" was a meme at the time)
I don’t really see this as all that controversial.
Indeed, isn't this basically standard for people on their deathbed? Morphine for the "pain" but really is going to help their heart and organs stop.
In this case, the King's doctor essentially gave him a very large speedball without the consent or knowledge of either the King or his family. The doctor decided to do this unilaterally to ensure the King's death was announced in the "right" newspaper. That's quite different from giving someone a morphine drip (usually with the family's knowledge/consent) to speed up their demise.