UAF and Hope Not Hate are run by Communists. The SWP, for example, states that it stands for "revolution not reform' i.e. a violent civil war (or do you think they mean a twitter campaign?).
30 members of TUSC blocked Nigel Farage in hios HQ in Rotherham but they only got 61 votes as against 1,143 for UKIP in a recent election.
Why should fringe communists + a supportive liberal media be allowed to stir up hatred and violence against a popular democratic party?
Oh yes, to silence them.