I disagree, OP. MN has a very robust policy on moderating trans issues (there's a pinned thread setting this out at the top of FWR), and transphobic comments are always deleted if reported (and they are always reported - twitter indicates that there's a group of people who watch MN obsessively solely in order to screenshot/report things). FWR is also the only part of MN which has a "3 strikes and you're out" rule for banning people with repeated deletions.
Re. some of the comments upthread, it should be pointed out that sometimes decisions on human rights are a zero sum game.
For example, you can't have a legal system which allows the foetus an absolute right to life (thus compelling women to carry unwanted pregnancies to term and give birth, with all the attendant health risks, against their will) and simultaneously allows women the right to bodily autonomy, in particular deciding whether they want to give birth (at he expense of the embryo/foetus). The legal system has to come down on one side or the other.
Unfortunately trans rights (as opposed to the general human rights which we all share) are one such zero sum game in certain areas (I would argue a very limited number of areas, such as sport and women's prisons). Most of the time it doesn't matter, but there are a few areas where the decision as to whether the slogan "transwomen are women" is to be taken absolutely literally, or seen as a polite legal fiction to apply in almost all, but not every circumstance, has crucial practical consequences.
For the avoidance of doubt, the current legal situation as enshrined in the Gender Recognition Act and Equalities Act, is the latter. In UK law as currently constituted, gender reassignment is a polite legal fiction, applicable in almost all circumstances, but not all, and organisations can apply for single sex exemptions (sex is also a protected characteristic) where it can be argued that these are proportionate and necessary.
As I understand it, some members of the trans community (not all) want to replace gender reassignment with gender identity (a looser term, with no gatekeeping to check that people are acting in good faith), and to repeal the parts of the Equalities Act which allow for occasional, proportionate exemptions on the basis of sex.