>Is there any way to forbid such people to speak in the open air? In the Netherlands and Brittain (and other European countries as well) only since very very recently the government is able to 'deport' those people to where they came from. But what to do with people who are born in the country and have no other passport?

Indeed, there is no difference from a Muslim Cleric inciting violence to a Christian Fundamentalist doing the same. In Netherlands and UK he would be deported.

In the USA, the Federal Communications Commission (FCC) has jurisiction over Radio and TV. Howard Stern, a known radio entertainer, has been fined in the past for using inapropriate words. Would they do something in this case? Sadly, I doubt it. IMO the TV network that briadcasted this incitement to violence should be fined and he should be reprimanded, fined and warned.