Mob justice over what people said years ago is very dangerous. And due to the global nature of the internet, it is very hard to get the mob off your back. It seems many students have been denied their college admissions due to stuff they tweeted as a teenager. It seems in the modern world felons deserve redemption, but bad tweeters do not. Not to mention that cancelling people over what they said in the past is so stupid, that if applied consistently, will lead to funny scenarios. For example, if teenagers should be punished for their past tweets, why shouldn't be Joe Biden for saying on the record that he doesn't support same.sex marriage in the 2008 VP debates. This is not even counting what opinions biden held in the 20th century.
It seems that we have come to a point where you simply can't speak on certain topics, neither in the affirmative nor in the negative, and so most people end up saying what will keep the mob at bay. Case in point, all the people attacking JK Rowling do not want to say that any man who self ids as a woman should have access to women's private spaces.
How many of them have still been denied after showing genuine remorse for their views? Nobody is owed a college admission.
> all the people attacking JK Rowling do not want to say that any man who self ids as a woman should have access to women's private spaces
Nobody's saying that men who falsely claim to be women should have access to women's spaces.
What are they saying?
You don't see people saying "trans women are biologically female" for a reason.
What does it mean for these categories to be social constructs? What criteria makes one a man or a woman?
That's up to the society, hence their definitions as social constructs. For example, when you shop for dresses, do mostly men or women come up? Articles of clothing by themselves are not tied to the biology of a person's sex... meaning a vagina/penis is not required to wear a dress.
But most of society (as it is now) has deemed that woman are associated with dresses, while men are associated with suits. That image is now changing, although slowly, with trans and other non-binary genders.
An easy way to see this is to ask yourself if you think it's acceptable for men to wear dresses? If so, ask why we don't see more of that in the workplace.
So, if someone identifies as as man, but society disagrees, is that person a man? What reasons would a society have to change their criteria to include this person in the category of "man"?
Marriage used to be strictly between a man and a woman. Now society says it can include homosexuals. Women used to stay at home to take care of the house, while men worked at jobs to provide for the entire family. Now society says both roles can be taken up by both men and women. Black people used to sit at the back of the bus, and now anyone can sit anywhere.
I mean, society constantly changes. We see it in history, we even see it today within our own lives. Places like Saudi Arabia are currently having their own version of woman's suffrage even as we speak.
So given this, in your example person, I would wager that society would deem that person not a man, since the hypothetical society has already decided it that way. But that's not to say that person will give up on not being recognized as a man. Our human history has shown us that we don't just stop at an idea, some of us go all the way to pave new rights for entire future generations to come.
Whether or not society adopts the new definitions, well, that's up to the people living in it.