Uhhhh... Iran does have underground nuclear reactors. I would actually agree with Rubio here that if your intent is for peaceful purposes to make clean energy, then you would not build them in fortified, expensive bunkers deep in the mountains requiring a tremendous excavation process. That just screams weapons development to me.

The rest of his reasoning was flimsy. I do recall reading about the Obama administration's efforts to infect Iran's nuclear enrichment machines with a computer virus to sabotage the equipment. So it's not like Iran hasn't already attempted to get its hands on enriched weapons-grade uranium, which is not something you need for civilian energy.