Brzezinski is a prick, that's obvious from his comment, especially for presenting a US shootdown of Israeli air force jets as payback for a case of friendly fire (i.e. the Liberty incident, which was shown time and again to be an accident, for which Israel paid compensation to the victims). However, he has no idea what Israel and the U.S. are planning or not planning. I doubt Israel would fly over Iraqi airspace if they thought they would be engaged by the USAF. Given that the Israeli and US armies are jointly drilling for missile attacks from Iran, my feeling is that the US will not try to stop Israel if it decides to go it alone. Sane people are well aware of the existential threat that a nuclear-armed Iran would pose to Israel, and I can't imagine any American President acting in a way that would facilitate another Holocaust.
U.S. says working on initiative to de-escalate Syria fighting, with focus on Aleppo (Reuters)
from the article: Brzezinski: U.S. should forcibly stop IAF flying over Iraq to reach Iran