Does that about sum it up?
I'm not following your logic. Attacking al Qaeda and Syrian Sunni Arabs bent on fighting the American infidel in Iraq would have cost Assad thousands of dead Syrian troops and billions of dollars in equipment and infrastructure losses, while making it easier for the US to invade Syria and topple him *and* making internal rebellion more likely by Sunni Arabs angry at him for aiding the American infidel's efforts in Iraq. How did not fighting these nutjobs lead to the current rebellion, which was partly inspired by the NATO intervention in Libya? Uncle Sam practically wiped the jihadists passing through Syria. Saying that Assad's policy of not fighting Iraq-bound jihadists was a mistake is like saying it's a mistake to get out of the way of a herd of stampeding buffalo.
The Saudi royals are nuts to give the Muslim Brotherhood a foothold in Syria because it will provide a base on the Arabian peninsula from which the Ikhwan can train and indoctrinate Saudis to subvert the rule of the al Saud family. It brings to mind the German decision to let Lenin pass through Germany in order to take Russia out of the Great War. It's doubtful that either Hindenburg or Ludendorff thought then that an imaginary Soviet Union would proceed, over two decades later, to inflict on a rearmed Germany, most of its 8m dead, while making the eastern half of Germany its vassal state. The difference is that an Ikhwan revolution won't stop at the eastern half of Saudi Arabia.