Isn't the problem that there are two types of anti-trans groups - first type is the reactionary, small-minded conservative, who may also be homophobic, racist, anti-choice, unthinkingly prejudiced against all sorts of groups or concepts alien to their narrow viewpoint. This is where the pro-Trump types sit.
The other group is the gender-critical feminist who actually spends a lot of time considering, weighing up, reasoning and is generally on the side of the less privileged, LGB / ally, pro-choice, anti-racist, likely to be fighting for the rights of those who don't have them. This is the MN type.
Usually, there is not much crossover between these types but in this case their views intersect despite coming from very different rationales. It's one of the reasons most of the liberal left or general fence-sitters can't bring themselves to grasp the issues - they are anti Trump therefore they must be pro Trans.