Diversity is NOT racist if you are basing in on determinants such as religion, gender, national origion, education or income levels.
It may be racist if race is a determining factor.
I don’t think it unethical to create groups that mirror society for some things. For example, a manufacturer assembles a focus group that mirrors society’s makeup to test reaction to a product.
Diversity is of course not racist, it’s the methods for creating it that might be. I believe that in most cases, diversity is a natural side effect of freedom and equality because different types of people end up in the same places if everyone is allowed to go there.