Comment 4 for bug 908841

This is a somewhat older "problem" . You need the "unmount" option because "safely remove" is an "eject" operation that sends a command to power off the device, and your card reader is powering down. . for some reason, the powers that be decided in their infinite wisdom that having both "unmount" and "safely remove" in the same menu was too confusing. So, you can use the CLI to unmount, or get an older or patched nautulus that restores the unmount menu option. Forcing a re-Scan of USB from the CLI might bring it back, too. This was a cosmetic decision that IMO, is unnecessarily dumbing down the UI.

More details here: http://ubuntuforums.org/showthread.php?t=1477247