You're right, it is confusing. See the problem we have in defining exactly what UNIX is? You know the situation is bad when you need a chart like this to explain it.
It’s not confusing at all, if it’s a derivative of ATT Unix it’s referred to as “Unix”. Why you thought that excluded OSX in your post above no one will ever know, and why you want to blur the lines between Unix and foreign clones like Linux doesn’t make any sense either. I’d recommend just keeping quiet on the matter to you finally figure it out, should that day ever come.