I think you are both missing the main point. The Iranian were given nuclear technology on the condition that they would not develop nuclear weapons.
The basic logic behind allowing countries to have nuclear technology is to limit the spread of the use nuclear technology for making nuclear bombs. The sales pitch is all nations can have the right to use nuclear technology for peaceful purposes, if these countries enter a treaty which limits their right to make nuclear weapons. Iran entered this agreement.

There are "problems with this", as example, you can sell someone a car by forming a agreement that the car buyer pays a down payment and they agree to pay monthly payments. What happen if this owner of the car is unable or unwilling to make these payments?
They lose their ownership rights to the car and a repo man shows up.

Now, the losers in the situation are the car owner and the lender- the car salesman is mostly unaffected. The car owner loses by getting a poor credit record and loses his down payment. The lender probably loses money because they paid the entire cost of the car, minus the down payment and monthly payments. Plus the lender has to pay the repo man who does the work of returning the car which the lender {needs to sell at a discounted price to recover some of it's losses. Another hidden cost is that with the higher the percentage of people who do not repay their loans increases the cost of making loans- these costs are passed on to general consumer of car loans, etc}.

Now, in regards to countries signing treaty agreements regarding nuclear technology the price they pay for violating their treaty is same price countries pay for violating any treaty agreement. In simple terms they risk war with other countries [which of course is costly not just the offender of the treaty but to countries in the region and the world in general].