Diversity is sacred to Democrats, so long as it is a synonym for Cultural Marxism. As for diversity of opinion, they are stringently opposed, because only one set of opinions can be tolerated — theirs. The leftist hate group Southern Poverty Law Center makes it explicit:

Alliance Defending Freedom (ADF) is pushing to entrench racist and exclusionary corporate policies under the guise of a socially conscious-sounding phrase: “viewpoint diversity.” …

ADF’s public relations and legal crusades are intertwined with Christian supremacist and white supremacist ideologies. Characterizing diversity as a threat to white Christian men, ADF is working to dismantle DEI protections [yadda yadda yadda].”

Diverse viewpoints are a threat to diversity and must be suppressed, in accordance with the Frankfurt School concept of “repressive tolerance.”

On a tip from Franco.