I think the controversy is summed up in the article. The problem, to me, is not so much that he has these opinions and gives them to his students, as that he doesn't present a balanced view of the subject. It doesn't sound like he's giving the other side of hte issue. His primary defenses are that he has the right to express his opinion. But the thing the school is investigating is the breach of their policy on presenting issues, against which I can't see a defense.
And, I'm not entirely sure how all his statements relate to teach geography. However, it may be that he just gives an opinion every now and then.
Like JP, though to a much less paranoid and fright-mongering extent, I don't necessarily have a problem with these issues being brought up in front of my children. We should answer the question of whether it's right to sell missles to Israel that we know are being used in a way that results in quite a bit of "collateral damage." But bringing up the question is not the same as answering, "No, this makes us evil." There should be discussion and the arguments for and against should be brought up in a non-aggressive, non-threatening manner.