A "51% attack" does not need to reach 51%, only exceed 50%.
Furthermore, the topic being a network, with a bit of programming the losing side can just go on running independently it's own share of it.
The ending made no sense at all. It's not like whoever gains 51% of the users will get permanent ownership of the whole network. Other parties can always increase their user base over time and challenge the 51%. Richard stalled Gavin and Laura for a few hours but they have every resource to come back later and create enough users to takeover the network. Richard didn't really gain and permanent wins.