Leaving a Secret Service issued laptop in a vehicle overnight should be unthinkable. I have always been much more careful with my company issued devices (not to mention my personal devices), and I have never worked in anyplace remotely as sensitive as the USSS.
Basic security practices should have avoided this incident to begin with.
No, it's fine. TPM and Bitlocker is all that is needed. The problem with using physical protection as protection is it only takes one mistake. With TPM and Bitlocker the only possible mistake is leaving it open. With lid closing turning on sleep the laptop will be a brick to any thief.
And we prosecute for taking pictures inside a submarine?
Put her ass in jail. Now.