Classic example of strawman this.
Even though Israel has weaponry capable of devastating destruction, there are multiple reasons genocide could not realistically happen “in about a day. Pointing to their milatary capabilities overlooks the complexity of modern conflicts and the meaning of genocide. While Israel possesses overwhelming military superiority, that does not mean the systematic eradication of an entire people could be carried out swiftly or without enormous global consequences.
A move of that scale would immediately trigger global condemnation, political isolation, sanctions, and possibly military intervention. Israel is deeply integrated with Western allies, so any such act would have profound consequences, limiting its political feasibility. If Israel has adopted a policy of genocide it would have to be a sustained effort over time, while maintaining it's support from the west. It would need a way to deny it ever took place. Recent historical genocides (e.g., Rwanda, the Holocaust) took months or years even with intent and planning, because wiping out an entire population involves more than having the firepower.