Unfortunately this is a rather silly statement as the routing table is basically just that...a database of IP addresses and how to get there as a next-hop. It would have made more sense to say "I saw the load on the router CPUs"saw the load on the routing tables" ...
Also, the whole idea of Nuclear power stations being exposed to the internet, even behind a very robust firewall, is ludicrous from a security standpoint. As the poster earlier mentioned, there are numerous backup systems and I suspect any remote-control capability would be via secure private lines or encrypted RF channels, not the Internet backbone. But, it is entertainment and otherwise is a well-executed show, so much more intelligent than the CRAP reality TV that is invading all the networks these days.