While the Iranian government calls forth the logic that it will attack Israel if the US attacks it, its apologists try to blur the rhetoric coming from Tehran. This really shouldn't be that complicated, and the continued fetish for the mullahs and their crazy nephew serves to drive those who would tend towards a stronger policy on Israel to respond in a manner that they might find surprising.
Christopher Hitchens, who has been a strong critic of Israel, and a vocal supporter of Palestinian rights, calls Juan Cole a liar for attempting to soften Ahmadinejad's threats towards Israel.
There is a balance to be had, of course. It is possible to support and admire Israel and criticize some of its policies and practices with regards to the Palestinians. It is also reasonable to acknowledge that Arab states have a hand in the plight of the Palestinians, and in many ways that critics like to ignore, have actively worked against constructive help for the Palestinians.
This is called being inclined towards complex thought, and apparently is not a talent nurtured by certain elements of the angry fringe. That's usually the case, but recently this bacteria has entered the mainstream and now fouls more than just its own sewers.
However, it's easier to find one thought and stick to it, regardless of the evidence. It's more satisfying to take one's own counsel than possibly be shown to have been wrong. Rational people, liberal people, welcome the opporunity to learn something, and accept that learning may contradict what once was thought to be true. This isn't a comfortable way of looking at the world, but it is a better way.