Epistemical Warzone

In "Privileged Standpoints/Reliable Processes" by Kourken Michaelian, I felt like I was being turned around in circles. For example, page 77 states that "only this sort of self-reflexive research, research in which the researchers focus a microscope on themselves, can provide us with a means of determining which biases are epistemically good and which are not." So I get that we should use more self-reflexivity to determine good methods, but in the end what we determine as good methods comes from our social location and morals, but then Michaelian goes on to discuss "epistemically good biases," but again, who determines if they are good? The author goes on to say, "Epistemically good biases, in other words, are biases that will tend to produce not simply knowledge, but knowledge that is (useful) for the marginalized." But who determines what is useful or even best for anyone? This all seems very objective in the end, where it relies on you as the researcher, yet somehow we can concur on general good or bad methods that are or aren't useful for a larger marginalized group...as you can see, I am lost in a theoretical and philosophical minefield.