Legality is what we're talking about, though. The government decided, against all reason, that this was something they needed to get involved with. So that means what whatever your definitions of sex and gender are, or whatever definitions the Wikipedia editors are accepting this week, they should not be used to discriminate against any individual, no matter how uncommon their physical traits and sense of identity may be.
I don't know why you think we're talking about legality when this whole thread was about biology. The legal status of one's sex is supposed to follow from biology, but the point is that this is an imperfect process at this time.
As for the legal issues, nobody supports "discrimination" in an abstract sense, but the point is that there's a strong difference of opinion on what counts as "discrimination". If "sense of identity" is all that's needed to trigger some discrimination clause, a quality that cannot be verified physically in any way at this time, then that's a recipe for abuse by bad actors.
