I don't really want to discuss the Mearsheimer paper much here because I am too close to it personally. If you want to see some of the debate it has provoked, Daniel Drezner has blogged about it extensively:
www.danieldrezner.com/blogSearch his site and you will find about a dozen links to articles that dissect the argument from all sides.
Let me point out, though, the crucial leap you made that is important. You argue that it should be ok to criticize Israel's policies, just as it is ok to criticize Sudan's policies, or those of any other country. However, in your original post, you talk about Israel's "manipulation of our foreign policy." That is not a criticism of their policies, that is a conspiratorial allegation, and one that almost no one ever makes in regard to other countries. (No one talks about Pakistan's "manipulation of our policies, despite the fact that America has been fairly consistently pro-Pakistan)
Also, Mearsheimer and Walt themselves never use that language in their paper either. Language like that is very close to language that has been used by anti-Semites throughout history, and thus should be avoided. By all means, argue against Israel's policies. But be very cautious before you start claiming there is some behind-the-scenes conspiracy that manipulates our country.