If he is not able to prove that he was just a spokesperson for the site, it would be difficult for him to not be charged with running the site.
It is actually the opposite of that. He does not have to prove anything. The prosecution has to do the proving.
I would still argue with that, as if the government finds out you are involved with a company and they see you only as part of the team, then they will likely accuse you for any charges . If you then claim to be the spokesperson, then their next step would be to ask you to give the details of the people running the site as you would essentially just be an accomplice to it. I believe they did confiscate all his computers and drives back in Feb during the raid, so they must have something on him from that, otherwise they wouldn't have charged him with it.
From one of his conversations on skype they also quoted him " You can give me a quick google and see that I started SealsWithClubs.eu in 2011 and amassed a considerable wealth with the increase in Bitcoin price, Micon wrote in a Skype conversation. I plan to relaunch the (Lock Poker) brand and make all players whole."
which doesn't sound like him being a spokesperson.