Some of my client use keyboard / KVM units that lock -- the keyboard does not work unless you have a physical turn-style key and can enter a password for the KVM.
Really, if someone has access to the machine, there is no secure way to prevent them from destroying the RAID. They could simply remove the drives, format from the OS, etc.
I wouldn't bother to install the Windows Intel Matrix Storage Manager. That will just give you more of the same problem.