The issue I was trying to get at (and that neila83 has explained) is not whether the ash causes immediate IFSDs - but whether engines operated in this environment have an IFSD rate > 0.02 per 1000 in the coming months.
Your point is valid however the point becomes moot when you end up with a fleet of aircraft parked with perfect engines because the airline has gone out of business.
As with all things in life there is a balance to be struck, those who take a position at the extremes of both sides are possibly being either too cautious or too reckless.