If you buy a train ticket and the train company cancels the last scheduled train, they are obliged to sort you out with a taxi home, or accommodation if they can’t get you home.
Making airlines do the same seems like a sensible move, and the people whining that it’s an outrageous imposition on the free market seem like dickheads. Or at least, people who’ve never been forced to buy a £200 last-minute flight home and an £80 taxi after their budget airline baled on them…
And in the event that this should drive budget airlines into penury – which is exceptionally unlikely, given their existing high margins – then at least it’ll wipe the grin off that horrible smug O’Leary bastard’s face. Which is worthwhile at any price.