Because it smacks of reality. Iran wants the elimination of Israel. So does this rabbi.
Why was the American Tokyo Rose welcomed by Japan in WWII? Because she was a treacherous liar and served the needs of our enemies.
And so it goes with this lying rabbi and Iran, whose government is a terrorist-sponsor, blood enemy of Israel.
And if it was merely a hatred of Jews that was the motivation behind it, there would be no Jewish Iranians (clearly there are as this rabbi went to speak to them and was welcomed by Iran).
What of his point that the policies of political Zionism is a violation of the Judaic Law?