I would be curious to see the numbers and whether they truly mean "diversity" or if it is being used as code for non-white. For example, would an all Latinx workforce be more or less likely to unionize? If they are using the dictionary definition of "diversity", that indicates something interesting about people's ability to empathize and work together with people of other races. If "diversity" is just a code for non-white, it might simply be a substitute for a variety of other socioeconomic factors that we know correlate with race that might impact an employees' likelihood to unionize.