> Sometimes, logic needs to be manufactured hand-in-hand with what's morally right.

The point I'm making is that not everyone agrees with you about what's morally right. In fact, most people in the US, at least, do not. If you want to effectively advance your cause, it is worth finding an argument for your claims which does not rely on moral precepts your interlocutor may not share.

As a side note, likening the existence of national borders to the institution of slavery is probably not such an argument.