A couple billionaires sparred again Twitter on Saturday, with Mark Cuban challenging Elon Musk over his view of positive special treatment.

It started when Musk responded to a quote tweet from venture capitalist Marc Andreessen lamenting that the US higher education is to “renounce merit in favor of affirmative action”, as is evident from Columbia Universitys decision to stop requiring SAT or ACT scores for its undergraduate applicants.

“Very few Americans seem to realize the gravity of the situation,” Musk responded.

The Twitter CEO’s statement prompted backlash from a number of people — including entrepreneur and TV personality Mark Cuban.

“When was the last time you asked a job seeker or founder their SAT score? Kids learn differently today,” Mr. Cuban wrote. “AI will play a much bigger role by analyzing skills/academics that contribute to future success. If the SAT is state-of-the-art, why not test potential employees the same way?”

Musk did not respond, but Cuban further elaborated on his position in a number of other responses to people who engaged with his tweet.

“Diversity is not about hiring less qualified candidates to check a box,” Mr. Cuban wrote in response to another tweet. “It’s about expanding your search to include ALL qualified candidates. Especially those who may not traditionally have access to your hiring or training pipeline.”

The debate over the role of test scores in college admissions and the importance of diversity comes as the future of affirmative action is as uncertain as it has been in decades.

The US Supreme Court, currently dominated by conservatives, could ban the use of race in college admissions with its decision in Students for Fair Admissions v Harvard and Students for Fair Admissions v University of North Carolina. The court is expected to issue its verdicts in June.

Affirmative action in the United States grew out of the Reconstruction era and gained a stronger foothold during the Civil Rights Movement as a way to try to ensure that non-white and non-male Americans were given the same opportunities as their historically privileged fellow citizens.

But affirmative action is broad unpopular with the American public, even though it recognizes that racial discrimination the leftovers a major issue, and with Supreme Court justices like Clarence Thomas set to have an opportunity to rule on the constitutionality of race-based college admissions this coming spring.

Colleges and universities have largely fought for the right to use race as one of a number of factors in their admissions processes, pointing to the benefits of building a diverse student population. At the same time, they are increasingly skeptical of the benefits of standardized test scores—which critics argue are biased toward wealthy students and is not as predictive of how well a student will do in college as their high school grades.