There's nothing "offensive" about comparing the actions and mentality of Israel to those of the Nazis. What is offensive is demanding that one country and only it -- Israel -- be exempt from those comparisons because it hurts people's feelings, or because it seems "bigoted" to compare them.
The whole point of the Nuremberg Trials was that the precedents set there would only have meaning -- i.e., be something beyond mere "victor's justice" -- if those principles applied to the actions of **all countries** in the future. Israel doesn't have some special, unique exemption from the imperative.