Obviously it was a good thing that it was banned, but I'm just wondering if it would technically be considered authoritarian.
As in, is any law that restricts people's freedom to do something (yes, even if it's done to also free other people from oppression as in that case, since it technically restricts the slave owner's freedom to own slaves), considered authoritarian, even if at the time that the law is passed, it's only a small section of people that are still wanting to do those things and forcibly having their legal ability to do them revoked?
Or would it only be considered authoritarian if a large part of society had their ability to do a particular thing taken away from them forcibly?
I think it is a bit unfair to give you shit for your question.
it is normal to confuse authoritarian system with restrictions of freedom. Because generally that is how it works. But not in this case...
Because it is the paradox of tolerance all over again. Technically it is authoritarian to ban slavery but it would be more authoritarian to allow it as people would own people... So on the scale of how authoritarian an action is, banning slavery is as anti-authoritarian as it gets and allowing slavery is as authoritarian as it gets. (Of course, a world without slavery and without any rules would be less authoritarian but... I think we know better than trying that with slavery)
I hope this helps in actually understanding the reason instead of being told what it is.