because he is giving extremist nutjobs credit where raw bigotry simply led them kinda sorta in the right direction. There are plenty of reasons to be opposed to muslim immigration than bigotry. Everywhere in Europe that has had a significant amount of muslim immigration there have been problems. Not racist clashing but culture clashes where the muslims are very clearly in the wrong. The most glaring example has been in the Scandinavian countries. Rape has been escalating dramatically and the increase is at the hands of muslim men raping non-muslim women. They see all these women who aren't covering up "properly" and who aren't part of the ummah so they come to the conclusion that these women are free to "take." Problems like this are happening all over. There are periodic stories of honor killings in the UK. FGM is increasing all over Europe. People are seeing this and seeing who is doing it and are coming to the perfectly reasonable conclusion that muslim culture is not compatible with their own.
There is a British pundit who said something that resonates with this issue. I credit him with the spirit of this if not the exact words. We are having all these problems with the muslim immigrants and liberals are all coming out declaring bigotry every time someone speaks out about it. Its killing the necessary conversation to fix the problems and it is going to cost the liberals politically in the long run. People are going to get fed up and side with the people who have been proclaiming the muslims are evil from the start.