The problem is as I understand it, not being an expert on this stuff, that a company only has to negotiate with a union if it's recognised within that company. That's why the IPA has very little muscle, despite being a helpful organisation, because it hasn't got the widespread recognition that BALPA has. Unions can't stop something that is completely legal and above board, such as the takeover of one company by another or as in the Buzz case, the sale of a company to another. If the company that's done the taking over doesn't recognise a union then there's not a lot you can do apart from do your negotiating in court. And you can only do that if labour laws have been breached. Distasteful and underhand as the whole business might have been, no laws were broken. All the union can do in such a case is to try and protect its member's interests and watch carefully to make sure all rules are observed.
MOL's hostility to unions is well documented, but given the fact that they've just lost their bid to stop some of their pilots suing over the union issue I suspect we will see a change there at some point. As far as I know it's illegal in the EU for a company to refuse to recognise a legitimate union if over 50% of the workforce are members and the request for recognition is made. It's not that BALPA can't or won't do their job in the face of O'Leary, they're doing (with IALPA) all they can to protect their members. But when you're being obstructed at every turn and having to go to court to get what's rightfully yours no matter how small - it takes time. Progress is being made however!!