I am sceptical as well… As far as a router is concerned, the destination IP is just 32 bits. The router examines the 32 bit number to determine whether it has a route that the destination IP address falls under. If it does, it forwards the packet out the appropriate interface, if it does not, it drops the packet and returns an ICMP unreachable. Most routers are intelligent enough, or programmed intelligently enough so that packets with inappropriate IP addresses are dropped.
Here is another way to look at it…
This is what your router sees (without the dots)
This is THE network address or as close to a packet with “no ip address” as you’re going to get
or 0.0.0.0 in decimal
And this is the highest number your router can recognize
or 255.255.255.255 in decimal
There is nothing that will fall outside of that. Even if you tried to send something bigger than this at your router, the number is simply going to go into other fields of the packet and get interpreted not as your destination address but something else (either source IP or part of the options field).
Tell your friend to visit www.ietf.org, read and learn RFC 791.