I'm amazed at how the UKIP's performance has made many people lose all sense of proportion, and become thoroughly mindkilled...

I bet the mindkilling predated UKIP's victory, and only afforded an impetus to action for those already mindkilled.

About half the discussion seems to be 'one UKIP supporter said something rasist/sexist/homophobic'.

Why do you find this surprising? That's the standard attack. It's simply background music.

Worse, a friend of mine who is a lecturer in sociology endorsed a plan to send bricks to the UKIP's freepost address, thus wasting their money.

In Western democracies, the Left fights for power and is serious about it. Any means available.

But if the UKIP supporters then send bricks to the left-wing parties, then all parties lose money and the postal system slows down.

When does the opposition to the Left ever respond with a little tit for tat? In the US, there are all sorts of people mouthing off big words about fighting government tyranny, while meekly standing by while their children are sexually assaulted by the TSA purportedly looking for nuclear weapons in their underwear.

I would have thought a lecturer in sociology would understand about not defecting and keeping the moral high ground, but apparently I was wrong.

What he understands that you don't is that his enemies won't fight back. If your enemies are fundamentally pacifists toward your aggression, why ever stop?