I'm guessing they are referring to a certain synonym for idiot/moron/imbecile/cretin/dolt/etc. which fell off the euphemistic treadmill
Yeah, that's the Linus "hard R" (he thought "hard R" referred to "retard"), but it's just wrong. "Hard R" is "nigger", in opposition to soft r ("nigga"). I don't think there's even a question, that's how hard/soft has always been used. Anything else is just confusion, I think.
That would be the “Linus Sebastian misconception”