Simple really....DS' comments possibly mean the current situation fits the "Affordable Safety" model....and therefore it was perfectly fine to fly in the Ash cloud...he probably would never do it himself.....
The claims I saw on the paper attributed to him stating that there is no data to show adverse safety in ash cloud is baffling.
This episode is interesting...a happy ending, but I can bet you these pilots would have something to say to Mr Smith...
YouTube - ‪KLM four engine failure from volcanic ash cloud‬‏