Can i temporarily unblock a blocked usb drive from the client side without changing or distributing policies from policy manager server?
No, it is not possible. Access restrictions to devices can be modified only from PMC.
If he has local physical access to the computer, he could reboot Windows into "Safe Mode" and then there would be no F-Secure protection running as far as I know. If the USB port is still working in Safe Mode, he could copy files between computer and memory stick.
Best regards: Tamas Feher, Hungary.