If I had to guess, it probably has to do with Boko Haram being a distant threat in a foreign country. We don't risk anything by calling them out. On the other hand, Islamic savages make up a significant minority that lives among ethnic Britons. If a white citizen of the UK says out loud that the savage wogs in their midst are, in fact, savages, then he risks the loss of his livelihood and social ostracizing from his countrymen, and he risks his life if the Vibrants catch wind of it.
As Sailer's correspondent said, sex slavery has a long and rich history within Islamic culture. That's in addition to waging war and murdering infidels mind you. The English Establishment is reluctant to take this ram by the horns because they fear accusations of racism. If anyone from the UK or Europe reads my words, allow me to assuage your fears by assuring you that Islam is not a race but rather a demonically inspired false religion that must be resisted to a martyr's end if necessary.
As long as Europe continues allowing Muslims to come in, stories like these will continue. If anything, it should be the Muslims themselves who reconsider Islamic immigration. Europe is slow to rile but when they make up their minds to do something, they tend to be quite thorough.