I told him they would have had so much more support and legitimacy if Israel attacked first
this is where I think you are mistaken. The Palestinian independence cause was about to be quietly erased and forgot after many Arab states normalized relations with the Zionist entity, and this was in process (Abraham Accords, ect) until the Al Aqsa flood completely derailed this diplomatic plan.
The atrocities committed by the IOF since then have sank normalization with Arab states for the foreseeable future, and attacking first allowed the resistance to capture valuable settler hostages. They would be in an even worse position with no leverage if the Zionists were allowed to start this war on their terms, though I understand that is cold comfort to the present reality of Gazans. They are on the frontlines of imperialism and all they can do is try to endure and fight.
probably like 70% of Americans would accept a military dictatorship right now even if it is a terrible idea