I'm not expert on weapons, so this is just a layman consulting youtube for knowledge and this guy says penetrating Fordow, in short, will require at the very least 1/3rd of America's bunker buster arsenal, which they may not be willing to expend.
Anyone whgom think that a 20 storey big airplane can enter a airspace protected by high mobiliilty high altitude SAM systems without at least double digit loss needs a brand new bridge parking not far away from his house, for very low price.
B-2 is a STRATEGIC BOMBER, means its deisnged job is to provide counterstrike capability in the even of full out nuclear war.
It was designed because B52 against S300 has single digit chance of survival to do the strike ( be clear , it is the chance for single way success), so they had to increase this chance to 50-70% for credible deterent.
It means in pracical terms a B-2 sortie against a single target deep in Iran has in best case 50% chance of SURVIVAL. This percentage include the case when the plane turn back.
Whole Iran looks like a large hide and seek wetdream for BUK units, doesn't matter the flight path, there is allwazs a chance to see a BUK radar pop up underneath the airplane.
Again , design target of B2 is like " if we send 20 of them then with sum of 320 nuclear bomb then at least 160 bomb will be delivered "