While I favor Israel in the ongoing strife over there, I doubt that the Arab Christians could hold the highest office in Israel, as that would be reserved solely for the Jews. So, it's not total freedom, just simulated freedom, which is better than they would get than if under Islamic rule.
I am unaware of any LEGAL bar to a non-Jewish PM or President. It thus appears to me that the non-Jews in Israel are no more 'simulated' in their political freedoms, than non-Christians in the US.