"A lot of people have been disturbed by the character of his social media because it is in the same areas that he does his scholarship. If it was a musician saying that global warming is a bunch of nonsense, who would care? It is because the tweets are an extension of his publication, they are central to his work and many feel they cross the line into anti-Semitism," Nelson said. "The anti-Semitism does (bother me) and what appears to be almost a solicitation of violence."