Of course it's a social construct, just like everything else that matters is. If you don't want your live to be determined by social constructs, you would have to live alone in the woods.
Yes, and it’s silly to act like you don’t know of people who care a lot about following the law, thank cops for protecting us, look down on migrants for not doing it the right way, condemn people who steal to make ends meet because theft is a crime, yet don’t care much about the policies that leave our fellow humans on the street to fend for themselves that are immoral, but not criminal.
That's still not a point at all, just like saying "maybe political change would be good". Like, of course there are incidents where common sense morality and legal practice don't match, that's where lawmakers should step in and change something.
Yes, and the point of this is to remind people that's an option. A lot of people get stuck in "life is how it is" and change seems impossible. It's important to be reminded sometimes that it's not.
It's really the exception for any aspect of reality to be operating with the approval of everyone affected. Things being socially constructed doesn't mean they are less real, or that they are somehow easier to change. After all, "convincing people that they should think differently about some social construct" is just a clumsy definition of politics.