The push for diversity is not that sinister, they just want the widest customer base they can get. Neoliberal diversity and identity politics lets them be moral without threatening their power base.

What we've seen from Amazon's anti-union efforts this round is that they are not sophisticated enough to be pulling some kind of machiavellian plot.

If unions are going to work in America, they have be able to navigate a diverse group of people. The American working class is incredibly diverse, more than the country itself. It's a challenge but it's not insurmountable. But the left/union approach to diversity and the corporate approach are completely different from each other and have different material motivations.