You can see why Pearson has made the revelation now. This "greater good"-style posturing could incite a few Tory supporters, and perhaps even parliamentarians, who are concerned about their party's stance on Lisbon. Who knows? – it may even drive some votes UKIP's way.
But it seems to me that the strategy is more likely self-harming. At a time when UKIP are trying to expand their appeal – by focusing on Islamism as well as Europe – the news that the party was prepared to step down from the electoral fray, over the latter issue, may also put some people off.
* By contrast, Nigel Farage claims that the offer was for UKIP to withdraw from the general election.