Yes, I think that's the point ! They release the source because they have to, but if it is useless, well... they don't care, that's all, no need to try to understand Sharp's philosophy with complex concepts ^^
Not that I even blame them by the way: some engineers are just told to have a Linux running on the platform they plan to sell, they manage to hack through it, and then they just forget about it.
Because you are working on a Linux kernel in Sharp does not necessarily mean you are an open-source geek or that you plan to broaden the view of your society. And even if you are, you may not have the possibility to do so.