There is still a difference between "we don't plan to stop selling arms to a genocidal country" and "we're so on board with genocide that this country commits, we'll do everything in our power to help them, also here's the generated video of my golden statue on top of the corpses we want to see, and I can't stress this enough how much I want those corpses".
On top of that, the left such as it is, have non-zero influence on Democratic party. Not a big one, but non-zero. And Palestine issue could be this pressure point, it has enough support to be one. You can't do anything with Genocidal Donny.