For national interest, read stability. For stability read growth.
All the other excuses are minor in comparison. The west (mainly UK and US, with Italy, Germany and France (who have separate issues and reasoning), didn't get to be world trading powers, by letting vast parts of the world descend into anarchy.
Why would the Arab nations, intervene, when either way they still have a commodity the world needs, and if it all goes pear shaped, they can point to the imperial ambitions of the west.
Now if a Gulf blockade happens, I wonder how soon China would start to vote with the west???
What really bugs me are the bleeding heart liberals who applaud when the west is accused of intervening because of oil, when the stability and freedoms they take for granted, are often because of intervention by the west, however ill conceived at times.