Looks like some of the cmdline parsing explicitly check for a space before the bootcode, specifically those that use functions in /etc/init.d/tc-functions
grub seems to strip away the rest of the line unlike isolinux, so just having "norestore" will fail detection.
As a workaround, you can either put something else before norestore, such as the suggested "quiet". However, if you still want verbose kernel messages during boot, you can just use any other 'filler' text, such as kernel (hd0,2)/tc_10/bzImage filler norestore