It is not at all unusual for Palestinian Arab academics to be far more radical than their politicians. The next generation of Palestinian Arabs, rather than being influenced by their more pragmatic parents and grandparents, are increasingly being radicalized and incited by their teachers.
Kassem has been a strong critic not only of Mahmoud Abbas but also of Yasir Arafat, thinking that they are not nearly violent enough. He was a professor in Jordan University in Amman and was fired for his criticisms of the university, and he has criticized his own university as well, delaying his career advancement. In other words he is just a hugely angry guy who transfers his hate for all things that don't conform to his worldview to his eager students.
But his biggest vitriol is dedicated to Israel - and Jews. In fact, his hatred of other Arabs is purely derivative of their perceived friendship with, or acceptance of, Israel. His website has some blatant anti-semitism:
The Jews have organized themselves in the US so as to influence the American public opinion and formulated the Jewish lobbies (interest groups) to influence the white house (the American president) and the congress (both house the senate and the house of representatives). Because of the money they have, the Jews started to finance some candidates for the presidency or the congress so as to have them elected, and started to publish items through the mass media or books and educational curricula so as to bring sympathy for the Jews and hatred for the Arabs.One of the ironies about Kassem is that he wrote a book harshly critical of the PA (which resulted in an assassination attempt against him) and he couldn't find any Palestinian Arab publisher willing to print it.
The Jews have capitalized on the ignorance of the American public and gave them so much faulty information. For instance, people thought at one time that the Arabs have tails and drink petroleum. The image of the Arabs has been distorted to a great extent, while the Jews have been enjoying an excellent image.
So he got it published - in Israel.