Be realistic. You could get every country in the world between the US and Israel to reject the use of their airports for the shipments, and you would find that the United States still has a navy. They would just sail the weapons right into Tel Aviv. All you would accomplish is slow down the process, and cost the US a little money. The Irish acting alone, which is all you will get, will accomplish far less.
If you ask the governments of Europe to choose between the NATO umbrella and letting the US do as it pleases, with Russian boots on the ground in Ukraine as we speak, that's an easy call. The Irish can throw a hissy because they don't need the umbrella. If Russia gets as far as London, the war and the Irish are already lost.
Let's not take our eye off the ball here. There are kids dying and starving in Gaza as we speak. We can discuss things like arms shipments later, when there isn't an urgent crisis on our hands. Keep the pressure where it belongs. Symbolic points on the board are a distraction we don't need.