I am surprised he would find any mac directly connected to the internet post 2003-2004. Unless you are connecting with 3g/4g directly, you are always behind at least a nat.
For IPv4, at least, if you connect via 3/4g you're going to be behind CGNAT. Far as I'm aware, there are no mobile operators left that don't NAT IPv4 traffic. IPv6 is different, of course, but I'm uncertain how well 14yo malware is going to deal with IPv6.