This whole business has been handled stupidly - no matter which way one looks at it.
Given that if one is flying in visibly clear air, there cannot be anything dangerous there (all ash related accidents were caused by somebody flying into the plume, and usually at night) the ultra prudent way forward would have been to ban night flight in the affected areas, and require ash clouds (if any) to be avoided visually.
This would have meant jets doing long haul night stuff having to be in/out of there before/after say sunset +/- 1hr, which would not have affected the overall picture very much...
IMC flight would remain an issue but there hasn't been any IMC around in this near-stationary high pressure area - which is why we have this "problem" in the first place!! Had we been having the usual strong SW airflow, the ash would not have come anywhere near here.
Robin is spot on IMHO. Every job tends to attract applicants who are self-selecting according to personality traits. So a "safety" job is going to attract a finnicky yellow-jacket pompous ISO9000-quality-manager type. You will never see Richard Branson applying for a post entitled "management of documentation for compliance with EU procedures for handling of hazardous chemicals regulations". These yellow-jacket types have been having a field day, and I think they are about to have their noses rubbed in some muck, publicly, and not a day too soon. They acted in a pompous high-handed manner and without any supporting data.
Had this lasted only 24hrs they would have got away with it. But this time they won't. This will be the stuff of business schools for some time... well, competent ones, anyway (if you can find one).