You're presenting a false choice between OK and not-OK. In reality it's a spectrum.
I am less concerned about the prospect of South Korea having nukes than North Korea if we are forced to choose. And I am less concerned about Israel having nukes than Iran, given the genocidal intentions the latter has expressed combined with the fact it's a theocratic dictatorship make it less than guaranteed that the MAD doctrine would apply.
I'd much, much, much prefer for Israel to also not have nukes, but those two situations aren't equally as bad.
I am less concerned about the prospect of South Korea having nukes than North Korea if we are forced to choose. And I am less concerned about Israel having nukes than Iran, given the genocidal intentions the latter has expressed combined with the fact it's a theocratic dictatorship make it less than guaranteed that the MAD doctrine would apply.
I'd much, much, much prefer for Israel to also not have nukes, but those two situations aren't equally as bad.