Why doesn't China block Tor? Isn't it easy as blocking all known public IP addresses?
It doesn't make sense to not allow the user to access certain sites, but allow Tor that can easily bypass that protection.
there are non public ip addresses and the tor team spends quite some time fighting the big firewall in various ways.
talk from the 23c3 about tor and china: https://www.youtube.com/watch?v=P6A7jLpL3Rs
No, not really: even if you could block all the known tor relays there are still the bridges that are exactly meant for this situation: bridges are like normal relays but their full list is not disclosed so it shouldn't be possible to block them entirely.
This is probably what he has been using.
[1] https://www.torproject.org/about/torusers.html.en