Closed Caption is a file that is different than a sub-title track. To be able to see captioning, you need a DVD player with closed captioning feature as well as a tv with that feature.
I authored a DVD for the government that required CC and to my surprise there are many DVD players out there that does not support CC.
The CC file is attached to the track inside DVDSP similar to a subtitle track but that's about the only similarity. Whereas you can manipulate the subtitles in DVDSP because they show up as little clips in the subtitle section of the track, CC are just embedded into the track. You can't manipulated inside DVDSP. You must open it up in Text Editor to change timecode info and text.
If your client wants CC on a video tape. Then technically it's not just title tool text on top of video cuz you can't turn that off. True CC requires that you be able to turn it off or on.
As for ripping the DVD video with CC, I'm sorry I don't have an answer for you about that but I would guess that you won't get the CC info if you ripped it off the DVD. But somewhere there should be the original CC text file (maybe a STL file) which you can embed into the tape master via a post/dub house. Again, I don't have any direct experience with this either.
Best of luck,
CHL
Chi-Ho Lee
Film & Television Editor
Apple Certified Final Cut Pro Instructor