Nmap Spoofing NSOCK ERROR
Solution 1:
Port 0 is a reserved port number that serves as a wildcard to tell an underlying OS to search for a free, dynamic port that can be used to establish connections for an application, saving developers the need to hardcode any port number.
So I'm presuming that's why NMAP could not bind its socket connection to PORT 0, but is rather redirected to another dynamic port.
More info: https://www.lifewire.com/port-0-in-tcp-and-udp-818145