> Iran isn't actually a nation of pure evil, they are looking out for their own interests
Exactly. I do my best to consider them an "adversary", not an "enemy" for just that reason.
> The risk is when they are backed into a corner where using a nuclear weapon increasingly makes sense.
I'd argue there are two risks: one is that this puts Iran in a position where, if the regime survives, they will feel (and rightfully so) that the only way to secure their position is to possess them.
It also makes the same statement to other countries in similar positions.
I don't think we have a better option, sadly, but it is a consequence of this action.
Also, I don't think this makes a rational case for use. For possession, yes. For threatening to use them under certain conditions, yes - but the only rational use case for deploying nuclear weapons is if your opponent has already done the same. This became the case when the thermonuclear bomb was invented.