I certainly hope you don't think it is alright to publish these letters or it tears at the very fabric of our society.
You have got to be kidding, right?
They are perfectly within their right to release it if they so feel like! As someone else pointed out, the production company didn't put any such clause on their letters, while Ryanair did when they were trying to resolve the matter with the producers. After they failed to meet an agreement, or gave Ryanair the chance of an unedited interview and/or statement, Ryanair did the best thing they could: release the documentation to the public, and let the public decide.