I think the idea here is being that if NAT is used, in the most common meaning, that usually means that the machine behind the router is not Internet-routable.

I think the idea here is being that if NAT is used, in the most common meaning, that usually means that the machine behind the router is not Internet-routable. There is no address which can be reached from the internet, that will go to the machine directly. (Which has actual security benefits.) Of course the abbreviation "NAT" really has a broader meaning, and one can of course set up certain network configurations where the machine would still be Internet-routable, even though NAT is used for something, or the other way around, etc. Is this what you meant? Judging by the link it seems so. A clarification could be important, so do you suggest perhaps that the question should have been more like "If my machine does not have a direct Internet address, due to NAT configuration, am I safe from ME exploits"?