The problem is Iran's obsession with nukes. Saudi is only interested in nukes because they expect Iran to complete their project (just like India and Pakistan have them because the other has them).Considering your obsession with nukes, why don't you care about Saudi Arabia's attempts to buy nukes?
And the reason I don't worry about Israel is they have had nukes since before the NPT existed so would have been exempted as an existing power if they signed, they have proven they won't use them even when Syrian tanks were close to rolling on Tel Aviv, and they are a functioning democracy.