They look, sound, appear and behave as a dangerous, anti-semitic, anti-Western group of hate filled people. Nothing to worry about? Google is your friend, they were rightly banned in the UK, not something we say often.
They are not banned in the UK - Blair and Brown tried it, but since the group wasn't doing anything illegal, they couldn't. Hence, it's absurd to fire someone, because his brother (not him) is a member of an organisation which you would like to ban, but you can't.