maybe because they are trying to act ethically toward a murderous neighbor that is conducting asymmetric warfare and those are the best tools to accomplish that.

or, maybe because they came to the conclusion that the repercussions on the world stage of even more horrific media coming out of Gaza is too steep of a price to pay.

i don't know which, but i do know it is naive to conclude that because they COULD end the war in a day and did not, they are driven by morality and ethical concerns rather than pragmatic ones.

because it would be admitting to the world that it has said weapons.

Israel has always said it doesn't have nuclear weapons. They would have absolutely zero sympathy going forward from any major nation if they decided to drop a nuclear bomb on Gaza, and they want that land so rendering that land uninhabitable might not be a good idea.