These ideas are equivalent. The belief that employers are lowering their standards in order to include more black people is based on the idea that any additional black person hired must necessarily be less competent than a hypothetical white person who could have been hired instead of them; that is, white supremacy. In Kirk's words: "You had to go steal a white person's slot to go be taken somewhat seriously."
They don't believe that there are black people who are qualified but weren't hired because of, for example, discrimination, because they don't believe "discrimination" exists per se, they just think of not hiring black people as logical meritocratic decision-making.