Arab states do not consider Israel an existential threat. Dennis Ross quotes an unamed Arab diplomat (Myths, Illusions and Peace p.278) "We know that Israel has a bomb in the basement, but Israel keeps it in the basement. On the other hand, if the Iranians get the bomb, they will wave it. This will cause problems...And as King Abdullah of Saudi Arabia reportedly told Vladamir Putin, if Iran goes nuclear, so will Saudi Arabia."
from the article: Turkey PM: If you don't want Iran to have nukes, give yours up