All the best workplaces that don't have a racism problem are the ones where lightly suggesting diversity training is met with hostility, denial, and sacking of the person suggesting it. Such actions really highlight how seriously said company takes concerns of bigotry at the workplace and proves they're giving it their all to make it as inclusive as possible.

I’m siding with the employee who was treated like a racist

Proving how incredibly not racist I am by taking incredible, personal offense at the suggestion of checking possible biases I may have as manager at a company with a history of racial biases, because I care about combating racism just that much