What exactly would El Al bring to an alliance? Very little, I think.
Royal Jordanian has been picked because it has a good inter-Arab regional network which it's going to develop - that's beneficial to Oneworld.
But El Al doesn't have that reach in the Middle East, for obvious reasons.
Star Alliance has publicly said that the Middle East is not a priority, it's too busy focusing on China, Russia and India.
Even if it was, Emirates is an unlikely candidate - Emirates has stated that it's not intrested in alliance membership.
Gulf Air, in my view, is a much more likely Star prospect. It has a strong regional focus and, like Royal Jordanian, is an Arab carrier with a fairly liberal platform. Gulf Air has declared that it wants to join one of the alliances and, now that it's reduced the complexity of its ownership, it's probably more free to make the crucial choice.