the one who might have been able to be reasoned with

You misunderstand the Democrats’ foreign policy if you think this.

Read a few books on international relations by members of the Biden-Harris administration and their mentors, friends, and predecessors. They are ideologically committed to US supremacy and hegemony internationally, at whatever cost. Broadly, this ideological tendency is called liberal (as in capitalist) internationalism and it is about preserving the “rules based” international order in which the U.S. is explicitly to remain indefinitely as the world’s sole hegemonic power. In this world view, the US is in the unique position of being able to be the arbiter of world affairs, due to its post-WII economic and military might and advantageous geographical position (easy access to both the Atlantic and Pacific oceans and lack of powerful neighbors) providing the US an unprecedented ability to govern worldwide. This supposedly makes the US the “only” world power capable of preserving international “peace” so long as no rival power is allowed to rise, particularly in Eurasia. The rise of a rival power to US hegemony is seen as a disastrous outcome because it will (supposedly) plunge the world back into WWI-style chaos. Overall, in their view, “order” (unipolarity) is superior to “chaos” (multipolarity), and “US-led order” is superior to all other forms of order, as in their view the US-led order is the only order capable of enforcing world peace, which they absurdly claim is what the US has been doing all this time since WWII.

One of the reasons they hate Trump so much is that he’s not from this ideological school; he’s an opportunist first and foremost and therefore has a chaotic effect on this US-dominated international order’s strategic imperatives. Trump can only be reasoned with on the basis of his opportunism, which will basically follow the whims of himself and his cronies, whatever those whims may be. The liberal internationalists can only be reasoned with in the framework of the long-term viability of US global hegemony, and their behaviors and goals are relatively more predictable as they have their own body of theory explaining all of that, which we can read (for example in the works of Brzezinski of the Carter administration, or Blinken of the current administration). To them, Trump is like a drunk driver who grabbed the wheel of the empire, because of his “America First” policies which they regard as short-sighted in that they play on various populist demands while ignoring and in some regards rejecting international “responsibility” of managing world affairs and suppressing rivals, (potentially) endangering the empire’s long-term stability. He messes up their timetables, finances, and commitments, that’s really the only thing about him they truly can’t abide. The fascist society he wants at home is the one they already created for others abroad, and which already has long existed for many at home regardless. Their “fear” is that the system of global US dominance they created will crash before they can get it back on track. They really do not care about the fascism part, which will not really affect them like it affects normal citizens.

This is all to say that “reasoning” with Democrats over Gaza would always have been impossible. Throughout the decades, they have dragged their feet on the issue, shedding a crocodile tear or two when the situation looks too bloody in the international spotlight, making tactical concessions occasionally, but all ultimately with a long-term strategy of allowing Palestine to be gradually whittled down, in which their ideal is that Palestinians stop resisting and Israel is ultimately triumphant in its suppression of Palestinian sovereignty and the issue conveniently “goes away” forever, a past tragedy they can pretend to be sad about while enjoying some newfound financial flexibility when it comes to the costs of maintaining and upgrading their unsinkable aircraft carrier Israel. Blinken didn’t give a damn about Palestinians in 1982, he essentially wrote that even though Israel was aiding a bit of massacres here and there it was still just a baby democracy that needs our support, and surely “someday” would be held accountable for its excesses. And now? Blinken is Secretary of State, giving Netanyahu a hug and requesting more funds for genocide and dressing his kid up as Zelensky for a Halloween party the next day. With people like this peppering every Dem administration’s top leadership for decades, whose careers all began long ago and whose records of views and behaviors are there for all of us to see, and likewise with their neocon friends, cousins, and business partners in every Republican administration salivating over war with Iran, the prospects of “reasoning” with any of them over Palestine are pretty much zero.

neoliberalism and “liberal internationalism”, also known as austerity, IMF debt, coups d’etat, getting bombed by NATO and signing Status of Forces Agreements