First of you have to define multiculturalism as you are meaning it. To me it is that everyone is different so we live with it. I do not always allow for another society's ethos to be equal to mine. Honor killings and vaginal mutilation as well as child brides I find abhorrent and unacceptable.
While the writer mentioned the arrest of a coptic Christian here he does not mention another cultural problem in Egypt and that is the crucifixion of Coptic Christians in Egypt. It is ongoing and has been going on before the video made news.
Germany and France have both noticed that multicultaralism have been detrimental to their societies and are trying to take steps to reverse that trend.