That’s referring to things like racial discrimination, which is definitely illegal. Insurance companies sometimes try to use proxies for race or other protected

That’s referring to things like racial discrimination, which is definitely illegal. Insurance companies sometimes try to use proxies for race or other protected classes to get around such restrictions, and that has resulted in a situation where any technique for evaluating people needs to show that it’s not being used as such a proxy. The goal isn’t to keep pools large, but rather to keep pool assignment fair in some sense.