Lets be realistic, Saudi air force is no where near as advanced as Israeli air force. Its not about bravery or cowardly, its about capability or lack thereof. There have been reports questioning if the US itself is able to totally destroy Iranian heavily fortified nuclear facilites without nukes or land invasion, because of the lack of a strong enough conventional bomb why assume we can?
Also, have you heard the phrase the enemy of my enemy is my friend?
Simply put, Israel poses no serious threat to Saudi national security, since we don't have a border dispute or a border for that matter with them. Iran on the other hand, we are already in war with them, and the battleground is Syria, Lebanon and Yemen, so yes I have absolutely no problem with Israel attacking Iran, In fact I think it should be a triple assault: US, SA and Israel. Either way, we will be dragged to this war whether we like it or not, might as well choose teams. You deal with your problems by urgency, nuclear Iran is an emergency.