This isn't about compensation, this is about care. Compensation is payable in some cases for delays, cancellations and denied boardings. Everyone agrees that compensation was not applicable for incidents resulting from the volcanic cloud.
Care, on the other hand, is something the vast majority of network airlines used to provide without a second thought. (Yes, there were always exceptions to this practice). The Regulators in Brussels considered practices of non-network airlines to be unfair since they didn't do the same thing. As this Regulation was being introduced the network airlines were nonplussed with these rules as they provided care anyway and, although nobody said so, they were happy to see some of the LCCs cost advantages being reduced. The LCCs hated this idea and fought bitterly. They lost.
So, airlines have an obligation to take care of their passengers regardless of the reasons for the incident. There is no time limit to such obligation written into the regulation, nor do I think there ever will be one. Delays of more than 24/48/72 hours are not common, but they do exist.
As noted above Cranair assesses all of their passengers a €2/£2 surcharge allegedly to cover these costs. My personal view is that they are overcharging for this and are being disingenuous if not deceptive (by blaming the Regulator for this charge) However in doing so they are self-insuring for these known and legally binding costs.
What did Cryanair get out of this? Simple, free publicity from the media in another feeding frenzy.