I don't think he's barking, no. While I don't see military intervention being an option, he surely has a point as to the cause, although he ought to go further.
The plain truth is surely that our entire foreign policy is wrong. Wrong because we go intervene for the wrong reasons, and then don't have a proper plan for how to replace the regime we toppled' wrong, because then after such failures we lack the conviction or the will to intervene again, when we should. The failure to respond to the crisis in Syria promptly with a stable and strong peacekeeping force as a prelude to negotiations has left Syria to deteriorate into a complete mess. Naturally, this instability is now spreading to other countries around it.
I don't think the answer in Syria was to have gone in and toppled Assad in 2011. But it ought to be obvious that doing little or nothing was not the answer, either. I think the solution above is the closest to the right thing, although unfortunately -- and here, Blair does seem to miss his own role in this -- earlier disasters in Iraq and Afghanistan, and to a lesser extent in Libya, have put us off from even trying.
As long ago as 2008 I had a theory that "all foreign policies are wrong". I think we're seeing that here. It was wrong to invade Iraq in the way we did and with no plans to follow. It will be wrong, now, if we stay out and leave the country and the whole region to burn in the fires of another Holy War. It won't stay "over there" for very long.