Listener Jay pointed out that when the selected startup disk is BootCamp, you will not be able to boot into Single User Mode.
You will also not be able to boot using any other startup option except for Startup Manager (Option Key) and Terminal Disk Mode (T Key). You can reset the PRAM (CMD, Option, P, R Keys) which will reset the startup disk to the OS X startup disk. Remember, this will also reset your date and time and remove the Open Firmware password if one was set.
When you boot with the option key and see the BootCamp Disk selected as default, this indicates that it is the selected startup disk. You will need to use a different method to attain the date/time and drive info.
You could use forensic Boot CDs such as Macquisiton, SPADA or Raptor to boot the system for imaging or preview. Just make sure that the solution you are using will boot a Mac.
Thanks to Jay for his email and tip.
Be Safe,
The MacDudes