This is an evaluative, subjective claim rather than a crisp factual one. Public reporting does show Nigel Farage publicly dismissed the Conservatives, Labour and Liberal Democrats as a "grand coalition of three social democratic parties" and as effectively indistinguishable, so the broad sense that he was sharply critical of the big parties is supported. But whether that criticism makes him "very rude" is not objectively measurable, so I can’t verify the adjective itself as true or false. Sources: The Guardian, "Ukip targets 'abandoned' Tory voters" (`https://www.theguardian.com/politics/2006/feb/21/otherparties.uk`); The Guardian, "Farage was rude but right about Van Rompuy" (`https://www.theguardian.com/politics/blog/2010/feb/25/farage-van-rompuy-michael-white`); High Profiles, "Nigel Farage" (`https://highprofiles.info/interview/nigel-farage/`).