The ultimate blackpill is just the unavoidable truth that the science isn't there and won't be there for likely hundreds of years at this rate. We aren't actually debating the ethics of turning men into women (or vice versa) but the ethics of turning functioning men and women into sterilized monsters that we all pretend are "complete".
Jim Sterling can shoot all of the dangerous, loosely tested, drugs he wants to in his body and change his name to "Kim Sterling", but he will clearly be a long way off from "a real, actual, functioning or believable woman". His quality of life won't improve and will just get worse until he has no more drastic measures to take left.