I think there should be an option to erase and restart the system in CCleaner to wipe the locked files.
I see where you're coming from, but feel it may be too complex for what is supposed to be a daily (or weekly or regularly scheduled) cleaner and more a job for a single-file-at-a-time deleter like unlocker. It would be harder for ccleaner to determine if a file is righteously locked or not.
In my opinion, not all locked files should be deleted outside windows, which is what a reboot and delete program is doing (example: windows system file can be deleted outside of the environment and boy does that make problems). It's not that ccleaner doesn't have the capably to do this - it used to with index.dat for ie and the need to restart explorer for the old systray entry, but these are special cases and done relatively without the user's intervention.
At minimum it does need the ability to delete on reboot several competitors have that feature and it has needed the ability for over a decade now. In the past just limiting it to IE's index.dat files never sufficed for me.
Although I don't know how "wiping" would be done in that "special" Windows mode.