If something that pops up on Pprune is enough to give an 'amateur' troublemaker the means to take over a plane, then it seems to me it's a vulnerable area that should be identified and dealt with. Airing it is only responsible - especially if the issue has been ignored by those in authority.
Anyone taking a professional approach to the task of hijacking is likely to have access to other resources, such as data from actual pilots and ATC staff, wouldn't you think? I don't think they're going to be scouring Pprune for handy hints.