I don't understand the issue. CC is not the same as SDH. CC does not even have to be SDH (although I guess they are in almost every case), and regular subtitles may or may not be SDH.

CC is simply a different way of encoding subtitles on a DVD, and just because CC almost always contains SDH, it does not justify flagging a regular SDH subtitle track as CC.

Also, subtitles can be very tricky. The Norwegian release of The Simpsons Movie contains four different Norwegian subtitles. The first is regular subtitles of the English audio, the second is subtitles for the Norwegian dub (I don't remember if this is SDH or if it only contains subtitles for signs and anything written in English in the movie), the two others are subtitles of the two audio commentaries.

It would be better if subtitles could be treated like audio tracks. That way we can select the language and content (regular translation, SDH, trivia, commentary, etc.) of each subtitle track. I would also prefer to link subtitles to the audio tracks, but I'm not really sure how that should work, yet.