It seems to me that if Israel calculates that Iran is likely to use the bomb, they will quietly tell Iran that they definitly will be nuked if they don’t abandon the program - quietly so as to allow them to save face with their public and to gain rewards for doing so. If Iran called Israel’s bluff, Netanyahu for example, could make a public statement - which Iran would know would be very hard to go back on - promising to take preemtive action by such and such a date. If Israel is facing extinction, why not? Who cares about criticism when the game is over?