Attacking DEI programs as hard as they do, GOP politicians tell on themselves. It's not fashionable or entirely helpful (for attracting voters) to be overtly racist. You have to be quiet about it, or at least have some plausible deniability. So as not to turn off the voters who are not okay with anti-Black racism.
When Republicans attack DEI in principle, they are broadcasting racism to their supporters in a way that they can deny.
That's probably why facts and reasonable arguments don't sway them. This arguments are not centered in their real objections, which are racist and designed to appeal to racist voters.
It's the same thing with LGBTQ issues. In the same Baltimore harbor collapse, several leading national Republicans called Pete Buttigieg, US Transportation Secretary and an openly gay man, a DEI hire.
It didn't matter that those charges don't make any sense, that he's one of the most highly educated, competent Democratic politicians serving in the Biden administration, or that he's done a crackingly good technocratic job at the Department of Transportation.
Those senior Republican leaders didn't call him a diversity hire because they actually think he's unqualified. They did it because they understand that openly deriding him as a gay man is not fashionable and that they need at least a little plausible deniability.
They knew that calling him a DEI hire would tell their supporters what their supporters want to hear, that they oppose equality for LGBTQ people, even for mainstream, very heteronormative gay man like Pete Buttigieg.
That's exactly the same thing they do when they call black people DEI hires. They're saying the loud part quietly. And you can't sway them with facts, because the facts literally don't matter to their arguments.