It should go without saying, but I'll say it that what you experienced is inexcusable and contemptible. It should not happen and I condemn it and hope it gets punished every time.
I've probably watched 5 or 6 hours of Robinson on various you tubes over the last year or so. So my knowledge is limited (I live in the US). But in those videos he has said more than once that most Muslim people are decent and nice people. It is Islam he opposes. He is hated and frequently threatened by the hard core skinhead racists who joined the EDL. But .. again I think he is a hothead and there are better avenues to try to solve the problems of extremism.
One thing that promotes the kind of violent intolerance you experienced first hand, is when the authorities: politicians, media and criminal justice system are perceived as excusing extremism and operating in a biased manner. The gross mishandling of immigration quotas, the inaction of police in Rochdale and elsewhere and the failure to act on things like female genital mutilation - all give the impression that people will have to solve the problem for themselves because their leaders seem clueless or biased. The less educated members of the white indigenous English population (and American) will then take the law into their own hands in stupid and inexcusable ways. In the US most working class whites probably couldn't tell the difference between an Indian Hindu and a Moslem. Hindus have been attacked by yahoos and it makes me cringe. But one answer to reduce the number of such incidents is for the legally constituted authorities to do their job. Other answers would include more contact, communication and education.
And it hurts me that I'm often not seen as part of that white population, despite having a white mother. That's what some people misunderstand about mixed race people, we can belong in more than one place, more than one community, but it's up to them to accept us, and sometimes they don't want to. Too foreign for the whites, too white for the Arabs at times.
My point is he knew who the EDL would attract. He knew it would attract skinheads and neo nazis. He's just trying to pretend he doesn't know. He is one of them, he is a white supremacist too. Nothing can convince me otherwise.