Whether or not they or the others are to blame is an argument that will be mulled over for a while on this erstwhile forum.
But to have nongs say that without regulatory approval, Tigerair shouldn't have been selling tickets only supports the notion that idiots frequently post on this site; I distinctly recall that every new destination on Jetstar's international network was sold with the caveat 'subject to regulatory approval'.
So are Tigerair's.
It's lawful. It may not seem right, but it's lawful.
So if that seems so irritating, go and shirtfront your local member and convince them to change the law as it currently stands.