I'm not sure if that's what it says. The way I read it "could care less" was used in the 1800s but with the negation in another part of the sentence. Modern usage simply omits it.
That's what the article says, but I can't see negation in the 1865 example:
> His bearing towards male acquaintances, of whom he knew little or nothing and could care less, was marked by an affectation of gushing friendliness, which overdid itself.
> His bearing towards male acquaintances, of whom he knew little or nothing and could care less, was marked by an affectation of gushing friendliness, which overdid itself.