The correct referent here is not social justice movements now widely agreed to be on the 'right side of history' but movements that *claimed* the mantle of social justice, which includes a much wider range of causes, many of which we now recoil from.
So the divide on this question among people who see themselves as progressives is: Is the trans movement the latest in a line-up of genuine liberation movements (civil rights, women's rights, gay rights) or more like deeply misguided causes progressives championed (recovered memories, eugenics, thought reform, etc.)?
You could say: time will tell! But it's hard to imagine that sterilizing gay kids, removing women's hard-won rights, and subverting core liberal-democratic principles and processes is going to end up in the Right Side of History column.
The witch-burners and inquisitioners also thought they were advancing the cause of social justice and had no doubt that they were on the "right side of history." Arguably, so did the Nazis. Believing one's cause to be just is virtually a requirement for subscribing to it. As Eliza states so eloquently, claiming that one is doing good is no justification for inherently inhumane behavior.
Exactly! The question remains: is this a real social justice movement?
The answer remains: no.
It’s a coordinated effort to have the delusions of a few men validated so that they can feel better about themselves.
These people are deliberately appropriating social justice aesthetics and language to legitimise their demands, but we see through it, and we see how their attempts endanger the hard won progress towards sexual equality. And we know that women are the truly marginalised group.
To many of us, this looks like the latest in a long line of attempts to keep women subjugated. And those of us who love fairness and equality will die trying to prevent that from happening.