Well what would Jesus do?
Would he support the capitalist venture that sees an American evangelical WWJD import sold at $9 a time? It's all guess work. My guess is that He would deliver His message and move on. But that answers the wrong question which is, What did Jesus do? There is an interesting answer here.
The Established Church is already in deep trouble with American ideas of Anglicanism but this is not an evangelical protest or even a Christian protest. I read one report where demonstrators wondered what the Vatican response would be thinking that St Paul's was a Roman Catholic Cathedral. Various themes have been added to the protest by a mixed bunch of people using Christianity as one of their weapons. When professional protesters move in they become a liability to the legitimacy of the original cause as demonstrated at Dale Farm. A similar community establishing itself outside St Paul's will lead to an increasingly intolerable situation with a high probability of violence which both sides of the initial protest want to avoid.
When Jesus was shown the coin His advice was clear, obey the law.