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

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. https://www.torproject.org/docs/bridges https://www.torproject.org/docs/bridges