You have no basis for your arguments though.
1. MAME is open source, so everything else should be? That's plain old fashion self righteousness. Being open source doesn't give you the right to tell people what do to with their own code, just because they use your code in a project. As long as your code is properly credited and used appropriately, its tough shit if you don't like what someone has done. Especially if there are no GPL/LGPL violations going on
In any case the problem should be with the people who compiled Mame ++ with Kaillera, not Kaillera itself.. Just because something uses Kaillera doesn't mean the developer of Kaillera was the one who compiled the binaries and did everything.
2. Kaillera was purchased by a third party. That party PAID for the legal rights to the work, including the closed source code. He owns it, he can do anything he pleases with it. It's his legal right to contest copyright infringement in a court.
3. While it may feel good to think Open K caused the new owner to do this, I don't see that claim being made by anyone but you. In the end it doesn't matter though, because if the Open K project is using parts of a closed source project in their own project, then the copyright holder has the right to contest it.. I don't know what the deal about not being patented within the first three years of innovation has to do with anything, but if the owner has legal ground, its tough cookies for them. When it comes down to copyright and patent infringement the person who can prove they came up with an idea and used it FIRST, usually wins. A copyright definitely helps in the owners favor.
But Open K just admitted themselves they were using the client module from the original Kaillera project, a closed source project. If that module was created and not released as an open source project, then they may very well have a legal problem. That's why they said they are waiting for confirmation to see what happens with the next Kaillera release.
The bottom line is they can probably get away with calling themselves Open Kaillera, however.. If it turns out the copyright holder can prove they are using any code he owns the legal rights to, no matter how long ago it was created or how long after creation it took to copyright/patent it, their distribution will become illegal unless they remove that code and use their own open source alternatives.