If I were to stop reading every anti-gun author, or every author who has made glaring errors about guns in his books...
Goodbye, Ed McBain; John Sandford; Elmore Leonard; Robert B. Parker; James Patterson; you get the idea.
Some are outspokenly anti, as shown by King's essay. Others show consistent anti tendencies in their books. If a non-LEO /non-criminal has or handles a weapon in a Sandford book, that character will either mistake a cop for a burglar, or get overly confident and hence shot by the bad guy. In a McBain story, any non-LEO with a gun will be a bad guy.
Patterson... how many times has Alex Cross either cocked or else lowered the safety on his Glock, anyway?
Griffin and one of his co-writers had a character who carried a Colt Officer's model in an ankle holster as his primary weapon, and who would top off said weapon by inserting a round directly into the chamber...
Leonard, one of my favorites, has given several characters SIGs because everybody knows they shoot faster than other guns... His (or his characters') words, not mine.
If I like the authors' stories, I will overlook such things. Some of them, I no longer read.