Yay another extremist swept under the digital carpet, problem solved - well NO. This will just shift this extremist content to other unregulated and unmonitored platforms that will not engage in debate, but blindly accept such things. After all, if people believe this kinda stuff, cutting of the head won't stop them believing, just shifts the problem out of the public glare, at least on the surface.
Actually it's been pretty conclusively shown that removing extremist content from mainstream channels pretty much prevents the ideas from propagating in the mainstream. If the cockroaches want to crawl under the fridge there's not much you can do to stop them but you can stop them from breeding on the table.
What if that 'extremist content' is pro-LGBT content somewhere else? What if it's criticism of religion? There's no consensus that those aren't equivalent to extremist content around the world, so such censorship does just as good a job at stopping what we once, in the West, considered abhorrent and obscene, as whatever we consider abhorrent today. I don't get how you can consistently square that circle.